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ABSTRACT
THE MATHEMATICAL BEHAVIORS DERIVABLE FROM THE
PROGRAM OF UNIFIED SCIENCE AND MATHEMATICS
FOR ELEMENTARY SCHOOLS
By
Sompop Krairojananan
This Case-Study is a comprehensive account of inten-
sive continual observation.of four 'USHES' classes at
Lansing, Michigan, during the nine weeks from late September
to early December, 1972. USMES (Unified Science and
Mathematics for Elementary Schools) is an activity-oriented
and integrated course in science, mathematics and social
science. Many units, designed to promote the problem-
solving skills of students in their attempt to answer some
major 'challenges', have been developed, and four such units
(Soft Drink Design; Dice Design; Designing for Human Pro-
portion; and Burglar Alarm Design) were selected for
observation in.this Case-Study with emphasis on.mathe-
matical behaviors which arose naturally from these courses
of activities. The mathematical topics observed were then
categorized into seven areas: Arithmetic, Algebra, Graph
and Tabulation, Geometry, Application.and Practical Mathe-
matics, Statistics or Physics, and Foundation of Mathematics.
The mathematical behaviors arising from these four USMES
:8 In
seven a:
units 52
Six
to a lo:
arcse we
data. 1
niques a
clildre:
scientif
was that
results
by recon
Uni
oriented
could be
rather t:
Despite ‘
Sompop Krairoj ananan
units were found to be distributed fairly evenly in all
seven areas, and thus it could be deduced that these USMES
units gave rise to a well-balanced mathematics program.
Since each unit aimed at providing a partial solution
to a long-range challenge, the mathematical problems that
arose were thus highly relevant and did not contain artificial
data. These problems were systematically tackled by tech-
niques as near to the 'scientific method' as possible.
Children were observed to have learned Just as much about
scientific process as mathematics. One outstanding feature
was that students had to verify the correctness of their
results by checking with the practical outcomes, and 923
by recourse to teachers.
Uniformity was not to be expected in an activity-
oriented almost-realistic program like USMES. In fact, it
could be observed that diversity of students' achievements,
rather than uniformity, was encouraged in these classes.
Despite divergence in.activities, all students in.these
four unitseventually learned at least the following
mathematical topics, which the l963-Cambridge Conference
had termed ”the bed-rock foundation of elementary school
mathematics," namely, counting and fractions, m
and invariant properties of geometric figgaes, real
experience in collecti_n_g 9.21:3, 222 9; Eaphs and other
visual displays of data, and the vocabulary of elementarz
logic.
THE MATHEMATI CAL BEHAVIORS DERIVABLE FROM
THE PROGRAM OF UNIFIED SCIENCE AND
MATHEMATICS FOR ELEMENTARY SCHOOLS
By
Sompop KrairoJananan
ATHESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
College of Education
1973
__ 3'
6? ACKNOWLEDGEMENTS
It is a pleasure to express my heartfelt thanks to
Professor William M. Fitzgerald, the thesis director as well
as academic adviser, for giving me such an excellent guid-
ance in every respect from the beginning to the end of my
graduate study at Michigan State University. I also
appreciate the invaluable advice given by the members of
the Ph.D. Committee at various critical stages of my
graduate program. Thanks are also due to Professor Earle
Lemon, Department of Theoretical Physics, Massachusetts
Institute of Technology, for giving me permission to do a
Case-Study on USMES, and to the Faculty of Uexford and
Pleasant View Schools in Lansing, Michigan, for giving me
such a friendly welcomewhile I observed the USMES classes
there. Mrs. Cosette Rodefeld, who typed this thesis, also
deserves a word of thanks for her cheerfulness and efficiency
throughout this arduous work.
Finally, I would like to thank the Mathematics Depart-
ment, Michigan State University, for giving me partial
financial support, and the Thai Government for giving me
the 3-year study leave.
ii
”
uiapt
TABLE OF CONTENTS
Chapter
1 mTRODUCTIONOOOOOOOO...OOOOOOOOOOOOOOOO0.0...
What is USES?O0.0.000000000000000000000000
Statement of the Research Problem..........
Justification of the Method Used...........
Limitation Of the StudyOOOOOOOOOOOOOOOOOOOO
2 mm OF WTED LITMTUREOOOOOOCOCOOOOOOOO
The literature related to activity-
oriented curricula.........................
The literature on the integration of
mathematics with science, social science
and Other cou89800000OOOOOOOOOOOOOOOOOOOO.
The literature on the philosophical
and psychological aspects of an activity-
oriented and integrated curriculum.........
The literature on the Case-Study type
of research in mathematics education.......
3 CATEGORIZING THE MATHEMATICAL BEHAVIORS
DERIVABLE FROM FOUR 'USMES' UNITS............
4 DETAILS OF THE FOUR CASE-STUDIES.............
The .SOft Drink D6819. unitOOOOOOOOOOOOOO.
The 'Dice D3819. unit.....................
The 'Designing for Human.Proportion' Unit..
The 'Burglar Alarm Design' Unit............
5 DISCUSSIm AND CONCLUSIW...OOOOOOOOOOOOOOOOO
BIBLIOGRAPHYOOOOOO00.000.000.000...0.0.0.0...
iii
Page
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34
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59
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107
156
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. . . . .
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awn
##
9w in area measurements. hperience in
drawing parallel and perpendicular lines for the Cartesian
Co-ordinate grids. Simple trigonometry for calculating
the height of classroom ceiling. Using the slopes of
right-angled triangles' hypotenuses to indicate the relative
'fatness' . Introducing P tan'l(y/x) as another way to
measure 8118198, ’ ‘ when P refers to the principal value.
(5) Statistics: Collecting data about the kindergarteners'
heights, the lengths and widths of 5th graders' faces, and
various measurements of a 5th grader's body. Calculating
the mean, median, mode and range from these data, and com-
paring the mean values of their leg-lengths, arm-lengths,
trunk-lengths, etc. with the measurements of classroom
furniture and fixtures to find out'why some furniture and
fixtures caused inconvenience to persons of children's size.
Writing up a physical profile of a 5th grader."
(6) Application and Practical Mathematics: Measuring
by means of a foot-rule, yard-stick or a tape measure.
Building a scaled model of a school (not completed).
Learning to make allowance when measuring a human body for
the purpose of making a garment (e.g., collar size should
be slightly bigger than neck-size.) Curve-stitching”
(e.g., mal
conics.)
to fit a 5
steel tape
from trigc
(7) g
limits: "
Discussion
5° Ill-p.11.
V0176. etc.
pairs (a,b
“my-town
t0 the rea
chi ldI‘en .
(l) A
mine an
(3,
Q 11111 Of
°’ Manly
finding Drh
thi ‘
8 elec
COuld not
Mtgetic
demnfitra i
P08i t1Ve
55
(e.g., making a hyperbole, a parabola, or other line-
conics.) Making simple furniture from wood and tri-wall
to fit a 5th grader's size." Verifying (by means of a
steel tape measure) the ceiling height previously calculated
from trigonometry tables.
(7) Foundation of Mathematics: An example of upper
limits: "The, library shelf should be at most 5 ft. high.”
Discussion of some lower limits" such as: the speed of
50 m.p.h. on a freeway, 18 years old for being eligible to
vote, etc. As mentioned in (2) above, the use of ordered
pairs (a,b) with ls as 5, 1sbs5 to identify 25 children.
Many—to-ona correspondence when mapping these ordered pairs
to the real numbers representing the heights of these
children.
THE BURGLAR ALARM DESIGN UMIT
(l) Arithmetic: Counting the number of turns when
making an electromagnet. Practice on fractions and decimals:
(Ex, To wind 20 ft. of (insulated) electric wire around
a nail of diameter 1/1: in., it required fifi 405.7,
or roughly 506 turns. Further, if these 506 turns of
winding produced a solenoid of 5", then the diameter of
this electric wire-333 -.01654", whose order of magnitude
could not be measured by a ruler.) The powerful method of
arithmetical deduction from indirect” measurements, as
demonstrated above. Scientific notation, e.g. 1.634 x 10-2.
Positive and negative exponents." Discussion of possible
error, (
of .0004
d=.0159
Informat:
'Off' anc
e.g., 0‘01
01' a batt
(2)
(imam
and the g
e.g. Curr
Pemtati
chfilnical
bination 3
thread
(3) LP
56
error, (e.g. , in the above example, there was a discrepancy
of .000” when checked against a standard Table which gives
d = .0159#",) and ways to improve the accuracz .of such work.
Informational aspect of integers, e.g. #26 wire; 0 means
'off' and 1 means 'on' in the logical circuit. Estimation,
e.g., obtaining a wooden block of comparable size to that
of a battery, when constructing a battery-holder.
(2) Algebra: Algebraic equation of one unknown, e.g.
(5.1416)d= 2:52-13. (This work included both the formation
and the solution of the equation.) Inverse proportion,
e.g. current oC W. The Inverse. Square Law.
Permutation of 5 elements in a circuit diagram: + pole, - pole,
chemical solution (of the battery), bulb and switch. Com-
bination n02 arising from all possible connections, e.g.,
bottom of bulb connected to bottom of battery,
bottom of bulb connected to curved side of battery,
threaded part of bulb; connected to top of battery,
e c.
(5) Graphs and Tabulations: Tabulation showing how the
magnetic force depends on the number of turns in a solenoid.
Study of First Difference to derive the growth-rate and
d003, , C e 8 e
No . of N o . of clips First
turns suspended Difference
50 9
100 17 8
150 25 8
200 55 8
250 40 7
300 45 S
350 39 -6
Ordered p:
graph 3' =9
In
Inversed
(4) _C;
the batter
center, d1
0! the co;
atMRS cu
(a bulb) ,
'"inging'
contact.
Relat
and discos
the + and
“mum.
between 2
(S) A
g
10118 dist
Vining e1
Contact (t
Circuits..
(6)
Electric c
heating or
en circ
57
Ordered pairs (8,72); (9,81), etc. giving the straight-line
graph y = 9x. Graph of the experimental results about the
Inversed Square Law.“
(4) Geometpz and Topology: Circular cylinder, (e.g.
the battery, the empty coffee can.) The circle: its
center, diameter, circumference =2nr. Cylindrical surface
of the coffee can flattened out into a rectangle. Parallel
strips cut from this rectangular sheet. Spherical surface
(a bulb). Mid—point of a line, (where the mechanical
'swinging' switch'was pivoted.) Discussion of 'geometrical
contact' vs. 'electrical contact'.
Relative positions on a circuit-diagram: connection
and disconnection. A topological line (any wire connecting
the + and - terminals.) Simple closed curve (a complete
circuit). Simple discontinuities. Separation and distance
between 2 planes. (The 'springy' door-mat and the floor).
(5) A lication and Practical Mathematics: Measuring
long distances for [electric wiring. Cutting empty coffee
cans into thin straigpt strips. Soldering intersections.
Winding electromagnets. Gluing springs and electrical
contact (tin-foil) to a door-mat. Manipulating logical
circuits.” Use' of a micrometer” to measure small distances.
(6) msics: Dry cells. Conductor (wire) and insulator.
Electric current, shown by the lighting of the bulb or the
heating of the wire. A complete or closed circuit. Switch.
Open circuit. Short-circuit phenomenon. 'On' and 'Off' .
Positive 2
series.
number of
Ohfs Law,
in series,
a battery.
Thelnver:
electric J
Gram
58
Positive and negative poles of a battery. Batteries in
series. Electromagnets. A solenoid. Magnetic force CK:
number of turns in the solenoid. External resistance and
Ohm's Law. Resistance of a wire ocits length. Resistors
in series. Potential Difference. Internal resistance of
a battery. Voltmeters. Ammeters. Magnetic Induction.
The Inversed Square Law. Electric terminals. Domestic
electric wiring.“ Logical circuits.
Gravitational pull. Spring constant and potential
energy of a compressed spring. Equilibrium or balancing.
Limiting friction.
(7) Foundation.of Mathematics: Abstractien (e.g.
noting relevant elements of an electrical set-up and
abstracting them into a set called circuit-diagram.)
To operate formally (i.e. to permute, or combine symbolic
elements of a circuit diagram, to do calculations by
referring to the diagram alone.) To gain.a.deep impression
of the cardinal numbers '1' and '2', e.g.
--”0NE'battery'd0esn't work; TWO work beautifully."
--”0NE:meta1-strip (in a battery holder) leads to the
short-circuit phenomenon; TWO separate metal-strips are
quite safe."
The J
Presentedl
records o:I
the teachvl
input dunl
um uniJ
the 'Dice:
tiOn' Uni
CHAPTER 4
DETAILS OF THE FOUR CASE-STUDIES
The full text of the four Case-Studies will now be
presented. They were written from the chronological
records of the writer's own observation, supplemented by
the teachers' logs in order to clarify some of the teachers'
input during these activity-oriented classes. The four
USMES units observed are: the 'Soft Drink Design' Unit,
the 'Dice Design' Unit, the 'Designing for Human Propor-
tion' Unit, and the 'Burglar Alarm Design' Unit.
59
I.
II.
The 95
Obser
The t
h
and r
activ
etude
' r
Brie-
V1 th
The H
cups
allot
Vedas
I.
II.
60
The CASE-STUDY of the “Soft Drink Design" Unit,
Observed at Wexford School, Lansing, Michigan
September 26 to November 28, 1972
The behaviors to be observed: Mathematical content
and mathematical process, which arose from the unit's
activities, class discussions, teacher's advice,
students' responses to questions, and other remarks.
Brief Description of the "Soft Drink" Group: Seven
students (four girls and three boys) were selected,
on a voluntary basis from a combined Grade 5-6 class
of about 90 children under a team-teaching situation
which involved three teachers. The teacher of this
Unit was one of the three, and she had actively
participated in the Soft Drink Unit of the USMES
Summer Workshop here in August. One girl student had
also taken part in that Workshop.
While doing USMES, they had a room of their own
with a kitchen sink, a) drinking fountain, a long table.
The Kool-Aid powder, sugar, spoons, pitchers, paper-
cups and paper-towels were provided. The time
allotted to the unit was twice a week (Monday,
Wednesday 1:50—2:15 p.m.).
h
'd
Six 5
and scienc
I
in these ell
problem we
61
Six students were at Grade 6 level in mathematics
and science and only one student was at Grade 5 level
in these subjects. No serious reading nor communication
problem was observed.
62
Activity 1: Mixing drinks and tasting these drinks
amogg themselves until each student came up with his
or her own 'brand' of soft—drink.
The children were experiencing a unique classroom
environment which involved a great deal of laughter,
manipulative skills in using household utensils, but
not without mathematical learning. They mixed different
kinds of Kool-Aids with various measured amount" of sugar
and water, tasted the new inventions, looked at each
other's colorful tongues, (the writer hoped that food-
coloring was relatively harmless), and sometimes left
the room hurriedly to avoid the near-nauseating feeling
caused by the grossness of certain inventions. Still,
all was done in good faith, and, after much experimenting
with the variable amount' of Kool-Aids that should be
used for a flag amount“ of water and sugar, every
student did come up with an acceptable formula of his
own. They learned that the success (popularity) of
one's drink depended on two factors: the taste and the
look of the drink. (One girl remarked that a drink
‘Throughout this Case-Study, the words marked "
refer to the mathematical behaviors observed, and those
marked " refer to the potential mathematical tapics
which could have been discussed in an USMES class, but
were not included in the observed unit.
which loo
they were
variables
(populari
and, as o
the whole
the drill}:
for disc:
in the re
independe
(1)
nature;
lime, col
(2)
titetiveW
(3)
measured
I‘ealize e.
(a)
by bottl€
The
idea that
Vari dbl e
63
which looked like vampire blood would not sell.) Hence
they were introduced to the concept of independent
variables‘ (taste, look) and a dependent variable‘
(popularity). The latter was easily quantifiable‘,
and, as one boy suggested, they were going to ppll’
the whole school to measure the relative popularity of
the drinks. The independent variable was brought up
for discussion, and, to the surprise of the two adults
in the room, the children discovered four (not two)
independent variables, as follows:
(1) the kinds of Kool-Aids (This is qualitative in
nature: the variable being strawberry, cherry, orange,
lime, cola flavors, etc.).
(2) the volume of the Kool-Aids used (This is quan-
titative, measured by a 'standard' teaspoon).
(5) the volume of sugar used (quantitative, again
measured by a teaspoon). Here the children did not
realize that there were many kinds of sugar.
(4) the volume of water used (quantitative, measured
by bottles of 16 fl. oz. capacity, or l-pint pitchers).
The majority of the children seemed to possess the
idea that "the color of the drink" was an independent
variable which directly affected the popularity of the
drinks. But, after some experimentation, they were
satisfied that the variables (1), (2), and (4) above
did take care of this extra variable. At this point,
the teacher could have introduced the concept of a
(D
cosgsit
later on.
and (4), 1
on color,
(I). (2) 1
ly, the t«
confoundiz
would be 1
Research 1
the Popule
must not 1
these are
there was
Pendent Va
”50’. they
in “lilting
from emer,
and more 1
Anot;
Vity Was «
Units whi4
requisite
& studentl
after a J
390011; th
Vill the 4.
64
composite function“, which the students would meet
later on. (The color of a drink depends on (1), (2)
and (4), and the popularity of the drink partially depends
on color, and hence the popularity, in turn, depends on
(1), (2) and (4), and perhaps more variables. Alternative-
ly, the teacher could have explained this in terms of
confounding variables“ in Statistics, a concept which
would be useful later on in such USMES units as Consumer
Research and Pedestrian Crossing. (If one says that
the popularity of a drink depends on its color, then one
must not introduce variables (1), (2) or (4), since
these are confounding variables to 'color'). In fact,
there was some advantage of treating 'color' as an inde-
pendent variable, as suggested by the children; in that
way, they could‘ggg,the concept of‘2.continuum“: e.g.
in.mixing drinks of a lime flavor, the whole continuum
from emerald green to light green could be seen as more
and more water was added to the solution.
Another concept the children learned from this acti-
vity was that of irrelevant variables‘. (All USMES
units which involve graphing will demand the identifica-
tion of relevant and irrelevant variables as a pre-
requisite.) Uhen the writer (of this Case-Study) asked
a student what the irrelevant factors were, he replied,
after a momentary reflection, “the color of the measuring
spoon; the kinds of containers used in.testing." "But
will the kind of container be a relevant factor in selling
65
the soft drink?" asked his teacher. "Yes," replied the
student, “because it would change the popularity of the
drink.”
One interesting behavior observed was the way the
children guantified‘ the ingredients used. They did not
use a weighing pan, nor a graduated cup to Judge the
amount of Kool-Aids and sugar; they Just used ordinary
teaspoons. This might sound unscientific, but they had
good reasons. "I have always kept this game spoon every-
time I measured the Ecol-Aids and sugar," said one girl,
"and one teaspoon means this full.” (She demonstrated
the amount.) So she got the basic idea of a 33$}; 9!;
measure‘, (which is, usually, arbitrary).
”But what happens if you want to communicate to
other people who have never seen your spoon?" asked the
teacher.
"Then I will say one-quarter, one-half or a whole
packet of Kool-Aid" replied the girl. 80 she viewed
the subject of fraction‘ from the utilitarian's vantage
point. This was precisely how fractions had been dis-
covered and used in antiquity: 1/2, 1/4, 1/8, ....
During the same period, another student proudly
told his teacher that he discovered a practical way to
'prove' (meaning 'verify') that 1/2 + 1/4 - 3/4, because
he first used one-half, and then one-quarter packet of
Kool-Aid, and he noticed there was a quarter left over,
and so he used up three-quarters of the packet. Earlier
66
that morning, he had been taught that 1/2 a 2/4 and
2/4 + 1/4 = 3/4 in a traditional 'math' period.
An USMES class could provide many opportunities
for practical verifications‘ of this type. The writer
once advised a boy (who ran out of Kool-Aid) to 'play'
with sugar. The boy was asked to divide a certain
amount of sugar on a large plate into 5 heaps, and to
divide the same amount of sugar on a second plate into
7 heaps. When the student added the larger heap of
sugar to the smaller heap, he could tell, Just by looking,
that the sum was approximately a third of the original
amount. This appeared to be more meaningful to the child
than the traditional presentation.l/5 + ll? 2 7/35 + 5/55
a 12/35, which had been shown to him a week before.
Incidentally, such 'playing' (with concrete objects)
would leave a strong impression in the mind of the child
--an impression saying 1/5 + l/7 # 2/12, or generally,
% + e , 8 1°
Also, during this 'mixing drinks' activity, while
the students were measuring water from the drinking
fountain, the teacher could have discussed the gate 93:
$19!” 93; a liguid-n-a very important topic both for
mathematics (rate of change) and for science (property
of fluids). Both a graduated pitcher and a stop-watch
were available in that school, so the (volume) rate of
flow of the water could easily be calculated, and
67
children would enjoy the experience of using a stop-
watch. This is also a very effective way to study
the concept of time."
Activity 2: Evaluating each other's drink:
Seven children produced seven 'brands' of soft-
drinks, and they decided that only the top three drinks
should be used in the general polling. A way had to be
found to choose the top three drinks from seven. After
some discussions, two types of evaluations were proposed
and adopted. (The evaluations would be carried out by
the seven students, plus the teacher and the writer of
this case-study.) In essence, the two methods of
evaluation were:
(1) Counting the,frequencies‘, by which each drink
was named first choice, second choice, third choice,...
and seventh choice;
(ii) Assigning a common maximum score to the drinks
which each rater liked best, and then.descending scores‘
at equal,interval to the next preference, until he
assigned a minimum score to the least-likeddrink. The
ranking“ of the drinks would then be decided by 3133
tgtal‘gggrg‘ each drink received.
They proceeded with the first method (counting
frequencies). At first, the seven drinks were named
Tom's drink, Kathy's drink, etc., but, for the sake of
modesty as well as impartiality, the sample drinks were
re-named
knew the
to be se1
this, a z
the names
column, a
his last
column.
this meth
beam. A
Sample :1:
(or the o
to fill u
rater had
Second 0r
I111ml abou
Peeple mi
Subdectiv
pm‘pOSe 0
drinks, b
thl
%‘ i“
b910w) ‘
A
(1
taking a
frOm fire
wwd
68
reenamed 'a, b, c, d, e, f, g', and only the teacher
knew the key to these code-names. A tabulation‘ had
to be set up to keep track of everyone's rating. To do
this, a student suggested that each rater should write
the names of his most preferred drink at the top of a
column, and proceed downwards till he wrote the name of
his last choice (seventh choice) at the bottom of the
column. It was the concensus of the class to adopt
this method of recording votes; and so the evaluation
began. All nine people were busy tasting the seven
sample drinks, trying to remember their pleasing flavors
(or the opposite) before walking over to the chalkboard
to fill up his own column of rating. Nearly every
rater had to taste some, if not all, drinks for the
second or even third time before he could make up his
mind about the relative merits of the drinks. Some
people might object that such a rating was highly
subjective, but it should be remembered that the main
purpose of this activity was not to rate home-made soft-
drinks, but to learn some mathematics from the experience.
First, the children here had the opportunity to see.g
matrix" in jag making (the 7 x 9 matrix in Table 4.1
below), an opportunity missed by most college students
taking a course on matrix Theory. Secondly, they learned
from first—hand experience the contrast of ordinal
numbers‘ (used in defining the rows of the matrix below)
and card
later or
Uhe
columns,
T5
Rate:
Choice:
lst
69
and cardinal numbers“ (used in counting the frequencies
later on).
When the nine raters filled up their respective
columns, a matrix was obtained:
Table 4.1: A Matrix relating the raters to
their preference in drinks
Raters ‘3
.d
m 3 a.
o «4 'H s: 'H o
e s 52’ a g 2 e a a?
Choices E-4 a M U) 0) 2 F3 5 m
1st c a a c b g a a
and a e c a c a c c b
5rd d c h f a f f g a
4th e g d d e e b b g
5th g f e g f d d f e
6th f b g e d c g f
7th b d f ‘ b g b e d d
The next job was to spot winners, especially
winners of lst, 2nd and 3rd places. The children read
from this Table the frequencies’ by which some drinks
were voted lst choice and 2nd choice. Drink 'a' was
t!» times voted to be lst, and 3 times 2nd, while drink
'c' was 3 times 1st and 4+ times 2nd. There seemed to be
little doubt that 'a'l should be declared the winner, and
' c' the runner-up. But the teacher quickly pointed out
70
that 'a' was still a shaky winner, since only 4 people
out of 9 (less than 50%) voted for it as their first choice.
"How many'%’does 4/9 correspond to?" asked a student, and so
they went on to have a mini-session on percentage.‘ Of all
the drinks voted to be lst choice, 'a' accounted for
44% of the votes, 'c' 35%, 'b' and 'g' 11% each.
A big problem arose when they tried to determine
the 3rd place winner. Looking at the 3rd row of Table
4.1, the children found that 'f' appeared 3 times, 'a'
twice, and 'b, c, d, g' once each. It was tempting to
take 'f' as the 3rd place winner. But, fortunately, a
student in the class sensed that it was wrong to ignore
'b' and 'g', because both 'b' and 'g' were voted top at
least once, while 'f' was never chosen top, and, for
that matter, never even for 2nd place. How could 'f'
be ranked before 'b'? Again, from the percentage point
of view, 'f' was put into 3rd place only by 33% of the
voters (3 people out of 9), and yet 3 other persons had
made it quite clear that they preferred 'b' to 'f'. (See
the first 3 rows of Table 4.1 regarding the positions of
'b'). But the f-supporters argued that 'b' was voted to
be bottom of the list 3 times, while 'f' suffered this
fate only once.
After some (heated) discussion, it was resolved that
the arguement 'f' vs. 'b' should be settled by the second
method of evaluation, i.e., by assigning appropriate
scores to each of the drinks according to the raters'
71
likes or dislikes. For example, 1 point could be given
to the drinks in the last row (7th choice), 2 points for
the 6th choice, 3 points for the 5th choice, and so on,
till finally 7 points for the lst choice on the top row.
It was decided by the class that, rather than tasting
the sample drinks again, they would make 932 93 the data“
in Table 4.1. The mere conversion of the data in Table
4.1 into another representation involving scores was a
good exercise in mathematics: it taught the children
one-one correspondence“ and Piaget's "reversibility 93;
ordering " ‘ :
lst choice —-> 7 points
2nd choice ——> 6 points
3rd choice ———> 5 points
7th choice .——.-; 1 point
It also taught the usual arithmetical skills“ _i_n_
multiplication and addition. In the next period, the
children were busy working out the scores obtained by
drinks 'a, b, c, d, e, f, g'. For examples,
Drink 'a': 7 points, 4 times 28
6 points, 3 times 18
5 points, twice 12
56 pts.
Drink 'c': 7 points, 3 times 21
6 points, 4 times 24
5 pts. 8: 2 pts,
once each .2
52 pts.
72
Drink 'f': 5 points, 3 times 15
3 points, 3 times 9
2 points, twice 4
1 point , once _1
29 pts.
Drink 'b': 7 points, 6 points,
once each 13
5 points, 2 points,
once each 7
4 points, twice 8
1 point, 3 times '_3
31 pts.
At this point, the 'b'-supporters clapped; so 'b'
was proved to be better than 'f' and hence 'b' won the
3rd place after 'a' and 'c'. (It was purely coincident
that the three top drinks were labelled like the first
three alphabets.) It could not escape the nOtice of any
observer that the children seemed to show more enthusiasm
to do this sort of arithmeticthan they would in a tradi-
tional 'math' class. When all this arithmetical work
was done, the children recorded all the scores in a
Table like Table 4.2:
Table 4.2: Scores assigned to the seven drinks
Drinks a b c d e f g
Scores 56 31 52 24 29 29 31
Although the dispute 'b' vs 'f' was settled, 'b'
still could not solely claim the 3rd place, because 'g'
75
came up with an equal score of 31. Also, unexpectedly,
'e' and 'f' shared the 4th place, with an equal score of
29. These two instances left a strong impression on
the children about egualitz‘ in mathematics: things
that looked and tasted so differently (such as drinks
'b' and 'g') could be said to be equal when we considered
another attribute (score) possessed by both. This subtle
meaning of 'equality' should always be emphasized in
applied mathematics. The writer has not high school
graduates who did not appreciate the equality expressed
in "Force - Mass x Acceleration.“
Something also seemed to bother the children of
this group.
--"How did you know that the top drink should receive 7
points, and not, say, 10 points?"
--"What made you decide that the last three choices
should deserve any point at all, since they would
probably not sell very well?"
The children's doubts were quite legitimate, and the
teacher should enlighten the children, once for all,
that all ggading systems“ (methods of assigning scores)
were, to a certain extent, arbitrary. A different
grading system, say,
lst choice -——-> 10 points,
2nd choice ——> 9% points,
3rd choice ———> 9 points,
7th choice ——-> 7 points.
74
might very well be applied to Table 4.1, and data quite
different from Table 4.2 would be obtained. This second
grading system would certainly narrow Egg gap‘ between
the best-liked drink, and the least-liked drink, but
would the ranking (ordering)" among a, c, b, g, f, e, d
be an different? It would be an interesting exercise
on multiplflng and adding fractions" to find this out.
(See results in Table 4.3).
Table 4.3: Scores obtained from another
grading system.
Drinks a b c d e f g
Scores 86% 74 841$ 701$ 73 75 74
So, the children could have been given the oppor-
tunity to discover that changing from one equal-interval
grading system into another did not affect the ranking
or ordering of the drinks. It would have been even
more interesting if the children were led to discover
why. This would be the children's first opportunity
to meet an invariance u_n_d_.g_g _a_ transformation,“ the key
to all modern mathematics.
[Think of the 7 scores in Table 4.2 as 7 geometric
mints“ on the number-line“. The changing from one
equal-interval grading system into another corresponds
to the translation" of the 7 points, together with the
75
shrinking” 93: the scale. These two transformations do
not affect between-ness” of points on the number-line,
and hence the ordering remains the same.)
The above geometrical” eglanation can easily be
demonstrated in the Design Laboratory, using a fairly
thick elastic band with 7 points marked off when the
elastic is stretched. The band is then bodily shifted
and allowed to shrink. None of the 7 points swap places.
Without changing the theme of this sub-challenge ,
the data in Table 4.1 could also be used as a spring-
board to introduce 'reasoning' by 2.9.33.2 2.; algebra".
That is to say, an algebraic method could be used to
show 3131 the ordering among 'a, c, b, g, f, e, d' did
not change when different grading systems were
assigned, provided equal intervals were maintained
between pairs of scores given to two consecutive choices.
[Let XI, 12, X}, 14, XS, 16’ X7 be the scores assigned
to the lst, 2nd, 3rd, . . ., 7th choices respectively,
with the condition
11> XZ>X3> X4>XS>X6>X7 > 0.
This condition should be 'equal interval', i.e., select
d > 0 such that
12'13’d 12-15+d
no. 01‘ 0.0
16-X7-d 16-X74-d
Score of drink 'a'
Score of drink 'c'
76
4 x1 + 3 x2 + 2 x“
b
+ X + X
3 X1 + 4 12 3 6
=X-X-o-X-X
1 2 3 6
'c' > 0
Therefore, 'a' 'c'
Since '> X
69
Xit> X , and X 'a' -
3
Hence, the score of drink 'a' is always above that of 'c',
of 21,
provided the above condition is satisfied.
regardless of the numerical scores 22, X}, X6,
The ‘b' vs 'f' dispute: Score of 'b' 8 X1 + X2 + X3 +
2Xh + XE + 317
Now XS . x7 + d
Is - x6 + d . (x7 + d) + d . x7 + 2d
and so 1, - x5 + d = (x7 + 2d) + d . x7 + 3d
X3 - x, + d - (17 + 3d) +‘d c 27 + 4d
x2 - :3 + d - (x7 + 4d) + d - x7 + 5d
xi - x2 + d . (x7 + 5d) + d - x7 + 6d
Hence Score of 'b' . (x7 + 6d) + (x7 + so) + (x7 + 4d)
+ 2(x7 + 3d) + x7 + d + 5x7
- 91.7 + 22d
Score of 'f' - 3x: + 515 + 2x6 + x7
. 3(X7+4d) + 3(x7+2d) + 2(xv+d) + x7
- 9x7 + 20d
‘b' - 'r' . 2d > 0. Thus 'b' > 'f']
77
The above algebra.may be a little too difficult for Sixth
graders, but, in view of the fact that USMES will be
extended into Grades 7 and 8 soon, this algebraic work
may be introduced with many subsequent benefits.
Activity 3: Controlling one of the independent variables:
Now that the 'best' drink had been chosen by the
group, mass-production, suggested a‘boy, should be
started immediately so that it could be sold to everybody
in the school. A girl was not too happy about the
suggestion, because drink 'a' had been voted lst choice
only by 44% of a very small group which was not represen-
tative of the whole school (She meant 'target population').
Besides, she felt that the first two choices (drinks 'a'
and 'c') tasted equally good. Drink 'a' had won because
it had an attractive color, and 'c' might have won.if
it were judged on.the basis of taste alone. The teacher
said that this statement (conjecture)‘ could be tested
out scientifically by controlling“ 933 independent
variable (look) and leaving the other independent vari-
able to function alone. One girl who had taken part
in the USMES Summer Workshop in Lansing recalled the
blindfold method to eliminate the variable 'look'. She
suggested to use the method, and the class than pro-
ceeded to rate 'a' and 'c' once again, but this time
each rater was blindfolded when he tasted the two drinks.
78
The grading system was the same as before: 7 points for
lst choice and 6 points for 2nd choice. The results
were tabulated in Table 4.4.
Table 4.4: Comparing drinks 'a' with 'c'.
a
Raters .3
0
use.
efifi’fi'éfiég
Drinks esssezsgss
Drink'a' 66766777658
Drink'c' 77677666759
The class decided that this result was inconclusive,
because
(i) it was a close race; the result 21.5217. b_e_ £133
332 chance‘. (Afterall, the rating was subjective).
(ii) When Table 4.1 was compared with Table 4.4,
it could be seen that there was only one person changing
the ordering of 'a' and 'c'. It was this person's voting
that gave 'c' the lead this time. The majority still
voted as before.
Although the result was inconclusive , the time was
well worth spent. It gave the children some idea how
to eliminate‘ or control a variable. It was also the
”1"
79
first time that the children experienced the formation
of a conjecture or gypothesis‘, conducting an experiment
3:3 1:353“ t_ne_ hypothesis, and deciding whether the results
were conclusive or not.
The teacher also pointed out that it did not really
matter even if this test was inconclusive. In a real
business situation, the store would sell both brands in
any case. Consumers are usually ready to switch to
another brand of the same product, if the brand of their
choice is sold out.
Activity 4: Preparipg a large quantity of the two kinds
of drinks for all their Eera (Sixth graders) to taste
and comment :
Apart from the purpose of communicating the progress
of the Soft-drink Unit to their peers who were working
on either Consumer Research or Designing for Human Pro-
portions, the Soft-drink group also wanted to survey
their peers' opinion on the drinks they had produced.
The teacher advised them to make the two top drinks
('a' and 'c') in large pitchers, so that their peers
might taste them and make comments. Thirty-two fifth
and sixth graders (those who were in the same home-room)
were expected to take part. From past experience, it
was estimated‘ that 1/4 of a paper cup of each drink
should be allowed for each person to taste and re-taste.
”How many cups of each drink would be required for 32
80
people?" asked the teachers. This was a problem on
ro ortion‘, and the whole class helped out to find its
answer:
"1/4 of a cup for one person.means 1 cup for 4
persons. 32 . 8 x 4, so we need 8 times as much, i.e.,
8 cups.”
”How much drink will be needed if the teachers of
the other two home-rooms want to take part too?" asked
the writer.
”There would be ample drink for two more persons,”
replied a girl, "because 1/4 cup for each person is
already a lot."
”What Mr. Sompop meant was how to figure it out
mathematically if there were 34 persons instead of 32?"
said the teacher.
”Let me see," replied the girl, "Two more persons
would require 2/4 of a cup extra,“
"What is 2/4?" asked the teacher.
”Two-quarters means one-half" was the final reply.
So the class proceeded to make the drinks by
.measuring out 8 times everything specified in the
previous recipies. First, it meant the pitcher should
be big enough to hold 8 cups of water. A boy suspected
that the pitcher was not large enough, because, as he
put it, {ppg,(linear) measurements‘, 1. e., the width
of the mouth and the height, of the pitcher are only
slightly more than double those of the cup, and they are
not 8 ti
it out I
by one,
that the
of watel
At
tionshi;
W
priate e
(1}
block w
is asked
every we
6 units
find out
“'0. and
(2)
3 C liné
cylinde;
can are I
take 8 I
81
not 8 times as much.” The teacher asked him to check
it out by measuring 8 cups of water and pour them, one
by one, into the pitcher. To his surprise, he found
that the pitcher could hold slightly more than 8 cups
of water.
At this point, an informal discussion on the rela-
tionship of linear measurements 955; volume/capacity
measures“ could have been introduced. The most appro-
priate experiences seemed to be:
(1) Starting from a certain cube, say, a Dienes
block whose dimensions are 3 units each, if the child
is asked to double the linear dimensions of the cube in
every way (i.e. to make a new cube whose dimensions are
6 units each from several smaller ones), the child will
find out that he needs eight smaller blocks, and not
two, and we write 8 as 25 or 2 X 2 X 2.
(2) A pop can or beer can should be introduced as
a cylinder”, and an empty (open) coffee can as a larger
cylinder. If the diameter” and heigt“ of the coffee
can are roughly twice those of the pop can, then it will
take 8 pop cans of water, not two, to fill the coffee
can. Again, it is a sort of M relationship"
between a linear measurement and the volume measure.
This second experience is necessary to convince the child
that such a cubic relationship exists not only for 31311”
rectilinear objects, but for 'round' objects as well.
82
The recipe for making one cup of drink 'a' was as
follows: 3 teaspoons of sugar, 1/4 spoon of orange
Kool-Aid, 1/4 spoon of cherry Kool—Aid, and 1/3 + 1/4
spoons of an 'undisclosed' flavor. (The students
insisted that each winning entry should contain an
undisclosed ingredient). As for l/3 + 1/4, they wrote
it this way not because they did not know 1/3 + 1/4 -
7/12, but they thought l/3 + 1/4 was an easier fraction
to work with: they put in 1/3 spoon, and then 1/4
spoon of the same powder. It would be more difficult
to estimate 7/12 of a spoon.
When the writer asked the students how they would
deal with 8 times the quantity (1/3 + 1/4) spoons, one
student explained:
"Four times 1/4 spoons will give one full spoon,
and so eight times (twice as much) will give 2 spoons.
Three times 1/3 spoons give 1 spoon, and six times give
2 spoons; but we want eight times, so we put in 1/3
spoons for two more times."
Apparently, this student grasped the intuitive idea
of a multiplicative inverse", and she also knew how to
use the distributive _l_a_w_‘ g; multiplication 9193 addition,
since she worked with 8): 1/4 and 8 x 1/3, and then added.
During this period of Activity 4, two more mathe-
matical problems arose naturally. Unfortunately, these
two problems were not pursued in details, and no) solutions
to the problems were given in class. The first problem was:
85
"Each packet of Kool-Aid (of the unsweetened type)
weighed 0.15 oz. and dissolved in,2 quarts of water
(sugar to be added afterwards). The teacher just brought
the class another type of Kool-Aid with sugar already
added: this packet (3.30 02.), when dissolved in 1
quart of water, was ready to drink. The teacher asked
what percentage of sugar was contained in the sweetened
type of Ecol-Aid.“
The second problem was:
"A.boy who was mixing drink 'c' in.a pitcher found
that the drink produced according to the recorded recipe
turned out to be too "gross“ (thick). So he poured out
1/10 of the content (of the pitcher into a glass, and
filled the pitcher up with water. He repeated this for
3 times, and the drink then had the clear and attractive
look he had hoped for. He wanted to know what fraction
of the original Keel-Aid remained in the pitcher, and
what amount of sugar must be added to maintain the same
level of sweetness as before."
The writer of this Case-study was of the opinion
that the solutions of these two problems should be
discussed and made available to the students while the
level of enthusiasm was high. Grade 6 is the proper
time to introduce algebraic techniques.‘* The solutions
of these two problems, as given below, would have pro-
vided the best motivation for learning algebra.
*
[Solution to Problem 1’: Let X (02.) be the amount
of sugar in each packet of the sweetened type, and thus
the amount of pure Kool-Aid in the packet - 3.30 - 1 oz.
*-
‘It should be pointed out to the children that the
symbol I used in.Prob1em l connotes a different meaning
from that in Problem.2. In Problem 1, the equation is
true only for ONE value of I, while in Problem 2, the
calculations will remain true for all values of I. This
was a point which SMSG decided to emphasize, and it was
one of the first deliberations of SMSG during its first
Writing Session.
Twi
oz. of 1
Thus the
Besides
good pr
also re
Sweeter;
|
I
(97.7%):
C!)
n
\w
I
anOmit
vent th
of {(001,
lst dill
in the +
lifter t
84
Twice this amount would function just like 0.15
oz. of the unsweetened type of Kool-Aid, therefore
0.15 - 2 (3.30 - I)
0.15 - 6.60 - 21
2X - 6.45
X - 3.225 oz.
Thus the percentage of sugar in the packet
' '22 x100 -§§§8x loo
' 3%?- - 97.7
Besides algebra, this problem would give the children
good practices on decimals” and long-division". It
also reminded the consumers that, when they bought the
sweetened type, they were paying mostly for sugar
(97.7%), and very little (0.03%) for Kool-Aid.
Solution to Problem 2‘: Let I (oz.) be the original
amount of Kool-Aid in the pitcher. Every time the drink
went through the diluting process, 1/10 of the amount
of Kool-Aid present was poured out, and so, after the
let dilution, X - 1%, X - I31 oz. of Kool-Aid were left
in the pitcher.
,After the 2nd dilution, the amount left
-r%I-rt (1‘3!)
- 'Ig'x - 'Ibgvx - 'I8% 1 oz.
85
After the 3rd dilution, the amount left
- as x - e as an
- «1% X - 18%” X - $883 1 oz.
Hence the new 'clear' drink contained only I853 or
roughly 3/4 of the original Keel-Aid put in.
The same fraction of sugar was poured out, i.e. 1% of
the original amount. Originally, he put in 8 times 3,
or 24 teaspoons of sugar, and so he had to add (18%” ) (24)
or jifglg’ or roughly 2 more spoons.
The same mathematics can be used to discuss some
problems in science, e.g. the problem of pumping out air
from an enclosed space.)
Going back to the activity of preparing drinks 'a'
and 'c' in large pitchers for 32 sixth graders to taste
and comment, it could be observed that both the prepara-
tion and the tasting went on fairly well. But the result
of this polling was again inconclusive. So the class
decided to give up polling on 'a' and 'c', and, instead
they would ask representative samples" from every grade
of the whole school to state their favorite soft-drinks
or pops. This immediately led to the tightening-up
of the definition of 'soft-drink' and using this concise
definition to design a questionnaire for the polling.
86
Activity 5: Defining 'Soft Drink' by examining the
mortise of two mutuallypxclusive sets: soft drinks
and non-soft drinks:
The teacher led the discussion and pointed out to
the children that before they seriously defined "soft-
drink", it would help to list items which were definitely
pp}; soft-drinks. In effect, the children learned of
two mutually exclusive sets‘ (although the teacher need
not say so). A beverage could belong to one of the sets
but it would never belong to both sets simultaneously.
Another concept which arose from the discussion of this
dichotomy was negation‘, and also the principle that the
unary Operation of 'negation' , applied twice, would
produce the original statement again:
“" V‘ P => P
The statement m m p took place when the class
decided against a student's suggestion that cider was
a non-soft drink. The student was somewhat sure that
cider contained alcohol. Although he was not totally
forbidden to drink cider, he was under the impression
that it was not good for children. Many argued that
cider was apple-juice, and although some brands of cider
might be slightly alcoholic, nobody got drunk with cider
yet. So the class decided that cider was go; a gig-soft
drink, and without any difficulty on logic, they con-
cluded that it was a soft drink.
87
The list of non-soft drinks was long, original, and
really interesting. (This might be slightly different
from an adult's list). _According to these children,
soft-drinks or pops did ppp,include the following:
pure water, whisky, brandy, beer, cooking sherry, milk,
tea, coffee, chocolate, ovaltine, fresh orange juice,
fresh fruit juice, soup, vinegar, alker-selzer, ...
(This is one very good way of describing'gflppp: listing
its elements‘).
Then came the first abstraction‘: "Soft-drinks or
pops are thirst-quenching liquids which (i) do not con-
tain alcohol, (ii) are not fully natural."
The condition (ii) above precluded milk, soups,
tomato juices, fruit-juices, etc., for being soft-
drinks or pops. The children also discovered one subtle
implication‘ derived from condition (ii): "Soft-drinks
or pops must contain artificial flavors and sugar." It
was this condition that differentiated between fresh
orange juice and orangeade soda. Also by this implica-
tion, tea and coffee and the like were precluded from
being called 'pops'. When the properties of the Non-
soft drinks were fully examined, it was comparatively
easy for the children to formulate the definition of
soft-drink , or m:
88
"A soft-drink or pop is a beverage which contains
soda-water or water (i.e. which is fizzy or not fizzy),
sugar, and artificial flavor(s)."
The (organic) formulation of a definition by the
children themselves after a great deal of pertinent
experience (i.e. mixing and tasting soft-drinks) was
another instance of the healthy method of teaching
mathematics and science in this program. Usually, in a
traditional 'math' or science class, definitions were
thrown at the children, who were then ordered to memorize
as many as they could.
Activity 6: Using the definition of "soft-drink" to
desig a questionnaire for general polling:
In learning mathematics and science, it is very
important to realize that the mere formulation and
memorization of some definitions are utterly useless,
unless ‘_t_hq_e_ definitions‘ 2;: subsequently mg _t_q derive
sometgpg _e_l_s_e_. Here, the definition of ”soft-drink”
could be put to use immediately in designing a question-
naire for polling sample population of the school. Since
'fizziness' and 'artificial flavor' were the two main
features of the "soft-drink" defined by the children,
the first two items in the questionnaire were:
(1) Do you like carbonated (fizzy, bubbly) drinks?
Check: ( ) Yes ( ) NO
89
(2) Read the following list, and write '1' for your
best-liked flavor, '2' for your next favorite, '3' for
the next one still, and all the way down till you write
'15' for your least-liked flavor.
Cherry Lemon, Raspberry
‘___ Grape ___.Root-beer Creampsoda
Pepsi Cola ___.Orange Ginger-ale
Coca Cola Blackcherry 7-up
Royal Crown Cola Strawberry Lime
: Other flavors
At first the children phrased item.#2 this way:
(2) Please fill in the blank space below the flavor
of the pop or soft-drink you like best: .
Soon it was apparent that, if they wanted to construct
a.preference/flavor matrix (like that of Table 4.1),
the sheer,piqu of this matrix might be prohibitive to
carry this work any further. The sample-population‘
was about 30 in number, and this matrix would be of the
size 30 x 30 if everyone happened to have a different
'favorite' flavor. By presenting the sample-population
with the above list, they could limit the size of this
matrix down to 16 x 16. (In the next Activity, they
discovered that even this size was still far too big,
and, in the last Activity of this unit, they used the
blindfold test to convince themselves that many of the
flavors above were, in fact, the same, and the size of
this matrix could further be reduced to 10 x 10).
90
The questionnaire also contained two more items,
both of which could lead to some meaningful mathematical
exercises. These items were:
(3) What is the convenient size for a bottle or a
can of pop?
( ) 8 fl. oz., ( ) 12 fl. oz.
(4) How much are you willing to pay for a 12 fl. oz.
bottle or can of soft-drink?
( ) 10¢. ( ) 15¢. ( ) 20¢
Item (3) should have furnished the most opportune
moment to answer the question "gps_t pp: 9112 i3 1 .f_l. 9_z_.?"
which must have bothered many children’s (and adult's)
minds for some length of time. First, many children
still think that this is a unit of weight, which is not
true. Secondly, all too many children, by rote learning,
verbalize '16 fl. oz. . 1 pint' without any appropriate
experience in dealing with the liquid content of 1 pint,
or 2 pints, or 8 fl. oz., etc. The writer introduced a
one-pint Coca Cola bottle into an USMES laboratory one
day. He asked a boy to fill half the bottle with water,
and said '8 oz.‘ He then asked the boy to half the
content twice, and the boy said, on his own, '4 oz.,
2 oz.‘ respectively. 'Now, you have to use your imagina-
tion a bit,‘ said the writer, 'Half this amount is what
we call 1 fl. oz.’ 'Oh, I see now,‘ remarked the boy.
Alternatively, any' teacher could have introduced
91
perfume bottles of 1 fl. oz., so that children might see
the actual content of this‘pp;p_measure.‘
The terms '8 fl. oz.', '12 fl. oz.‘ as introduced
by the questionnaire should also be called oneehalf pint
and two-thirds pints in order to have some practice on
fraction. For the boy mentioned above, '2/5 pints' had
a deeper significance than '12 fl. oz.', because '2/3
pints' produced in his mind an image of some liquid in
a one-pint Coca Cola bottle which was two-thirds full.
During the discussion on.pop bottles, mathematica-
artistic creativity“ could have taken place with regard
to the design of new kinds of attractive bottles, and
the approximate measurements of such designs. All kinds
of bottles could be brought into the classroom for the
children to examine qualitatively the curved surfaces“
of some bottles, and to study quantitatively their
diameters, heigpts, and capacities.
Another kind of container of soft-drink, the can,
could also be used in many ways as an apparatus for
teaching elementary mathematics. The prototype cans are
circular,pigpp cylinders.“ It would be easier to wrap
a piece of metal wire round a cylinder than to measure
the circumference“ of a two-dimensional circle by using
a piece of thread.
Hence, by using metal wires and a soda-pop can, the
attempt to discover,pgp.number‘3;“ would be less painful
92
than the usual method of using a thread and a 'flat'
circle on paper.
Finally, the last item in the questionnaire about
the prices 10, 15, or 20¢ for a bottle of soft-drink
could be used to generate a discussion on inflation which
is usually quoted in terms of percentagg increase.‘
The middle-class children may not be too thoughtful
about an increase of 5¢, but it represents an increase
of 50% (from.10¢ to 15¢) and 33fl% (from 15¢ to 20¢)
respectively. In Thailand, the inflation.has more or
less forced the coins of l, 5, and 10 cents out of
circulation (l U.S. 8 . 20.80 Bahts - 2,080 Thai cents).
The businessmen use the dirty trick of increasing the
retail prices in steps of 25 cents. It is not healthy
to accustom children to thinking of increases in steps
of 5s while only an increase of 1¢ is justifiable.
Activipy 2: An attempt to poll the entire school with
the questionnaires:
The original plan was to poll the entire school,
but as soon as the discussion about this ambitious
project started, they realized their limitations: the
quantity‘ of ditto paper required, the insurmountable
task of countipg‘ and analysipg‘ the returns, and the
pipq‘ it would take to carry out a large-scale‘ survey.
In any case, what was the use of acquiring information
pertinent to one school only? Two children hit on the
93
correct approach of getting the opinion of a cross-
section‘ of this school population from.K to 6, and hoped
that the cross-sections of other elementary school
populations were similar. Although the teacher did not
specificly give a formal lesson on stratified samplipg‘,
the children did learn the essence of this topic from
this experience. As events turned out later, the
responses to the questionnaires did come from a fairly
even cross-section of the school population.with respect
to grade levels and age-groups. It would have been
even better if these stratified samples were randomly
selected“. The writer sincerely believed that the
excellent co-operation between.the office and the class-
room teachers at Wexford would have permitted random
selections (pulling names out of pro-arranged bags) to
take place.
The survey group came across one difficulty when
polling the samples from kindergarten, grades 1 and 2:
the primary-grade children could not read most of the
writing in the questionnaires. This difficulty was
overcome by the service of three volunteers from the
Soft-drink group who patiently talked to the younger
children (K-2) about fizziness, the flavors of the drinks,
and the price, and these volunteers tried to record their
verbal responses as accurately as possible. One girl
remarked afterwards that it was delightful to talk in
'kindergarten! language once again, (e.g. 'bubbling' for
94
carbonation). But she was seriously doubtful whether
the younger children really knew some particular flavor
she was talking about, unless they had tasted the £221
t_h_ipg before, and in such cases it would be meaningless
to ask the question whether they liked that flavor or
not. So, even a sixth-grade student can deduce that
experience reigns supreme in education: It was unfor-
tunate for the overall result of this polling that, when
the younger students did not know any flavor, they
marked them as 15th choice (least liked) instead of
'no comment,‘ and hence the 15th choice here did not
necessarily reflect the quality of the drink. (See the
15th column of Table 4.5).
The sample population‘ was 32, but only 26 of the
returns (if counting both verbal and written returns)
were analysable. The class decided to use the Frequency
Method (See Activity 2) to analyse the returns with
regard to the p0pu1arity of different flavors. The
result is tabulated as follows: (See Table 4.5 on
following page).
It took the children.five class-periods to establish
Table 4.5, and they were somewhat tired at the end.
This feeling was not altogether bad, because it forced
them to take another good look at the 15 x 16 matrix
they had constructed, and to find an.offective way pq_
reduce‘ £13 pip: q_i_‘_ 331; matrix. (See the next Activity).
1!- .
'in. Fri:
Ii l.\: l| I .i
F. f‘ll
II: ’ "I.I
, 2nd, . . .l5th choices.
which each flavor was voted lst
was for checking whether the frequencies
votes)
(total‘
Pro quency by
The last column
Table 4.5:
were counted properly.
Total
\o u>xo m>xo u>xo u>xo u>xo u>xo u>\o
Votes NNNNNNNNNNNNNNN
N0 cu W\r443 c>.4 c><3 wxca enc: nice on
Comment
15th oaooomooaoommom
14th OOHHHMNOOOmHHNm
13th ooammmoasmaosmm
12th o1c>.4 c>cu N\r4 mseirn mtratu enc:
11th Haaaemoemosooom
10th NHHNNHHHOMNMHHM
9th OHMOHNHHNNHr-cmerm
8th HNOONNemmmaoaw-qm
71in mmoaaaommaammao—I
6th wxuxrn c>r4¢3 «\rn F'CUaH 01¢: K\r4
5th HNMMMONHCMHMNHFJ
4th r4!“ olin wxrq wxc>.4 04.4 n1.4 N\.a xxcu c><3 01¢)
2nd 01.4 d-Ln c>cu s-Cu N\r4(3 ri<3 r1<3
let .4 # «\rn otc>mother was wearing that day.)
Referring back to Figure 4.9 again, one could justly
14S
say that the sequence 6,12,18,24,50,56 might not generate
too much excitement (because that was merely the Multiplica-
3.9.2325. for 6), but all other sequences,” such as
7,15,19,25,5l would be a challenging pattern to the
children if. a teacher asked such timely questions as:
-- "Will an arbitrary number, say 85, be included”
in the above sequence? How do you check it?"
-- "Now if you call the next number (57) the £132;
1:_e_r_ip,” and one next to that (45) the seventh term, etc.
What number is going to be the 100th term?"
Surely there could be found some children who would
keep on adding 6 and tally every stage of the addition
until they finally reached the 100th term, and meanwhile,
11’ all the partial sums were correct, they would hit on
the number '85' somewhere along the line. Although
this was a good practice on addition, a more efficient
method did exist, and all it needed was the concept of
One-one correspondence ’ ’:
7. 13. 19, 25. 31, ...
11¢ 11¢
6, 12, 18, 24, 30, ...
The writer asked the 'Soft-Drink' Group (6th graders)
to solve the above two problems for the 'Dice Design'
Group (5rd graders) and some positive reinforcements
(Rare postal stamps from Thailand) were promised to be
Given to any 6th graders who could communicate the ideas
146
or at least the correct answers to the 5rd graders. All
the seven 6th graders got the rewards. After informing
the writer of the (correct) answers she obtained, one
6th grade girl said she was going to explain to the 5rd
graders in the following way:
"Look at these two lines:
7, 15, 19, 25, 51, ...
6,12,18, 24,50, ...
Do you see that the top line is always ONE more
than’ the bottom line? — (Yes). Do you also see
that'the bottom line is just the Multiplication
Table’ for 6? - (Yes). Now take the last number
In the bottom line (50); call it by another name,’
(the 6th term) is 56 or 6 x 6. The seventh term
is going to be 6 x 7, and you always do that for
the bottom line. Its one-hundredth term==6 x 100
= 600. The top line is always ONE more, so the
answer is 601."
"Why don't you try out your teaching method now? The
boy concerned is in the Design Lab perfecting his
'circular' track," said the writer.
The meeting was cordial and the boy did pay much
attention to her explanation, because it flattered him
to think that somebody else should take interest in his
circular track (Figure 4.9). But the 6th grader spoke
so fast that the writer was not sure if her listener
could absorb any part of her explanation except the
final answer '601' which he took for granted. In any
case, it $§_difficult for a third-grader to deal with 5
almost simultaneous mathematical operations: treating
100 as an ordinal number,’ multiplying’ 100 by 6, and
adding’ 1 to 600.
147
As for the first question: "Is 85 a member’ of the
ppp’ 7,15,19,25,51,57,...?" the sixth grader again dealt
with that on the basis of the one-one correspgndence’ with
the set 6,12,18,24,50,56,... They multiplied successively
all the natural numbers by 6, until they got 14 x:6 = 84.
The next product 15 x 6 ==9O was too big, so they went
back to '84' and added ONE to it. So they concluded
that '85' is in the set 7,15,19,25,50,... Apparently
it did not occur to this group of children that the two
inversed Qperations”: subtracting 1 from 85, and dividing
by 6, could have provided them with an easier test.
The A.P. 7,15,19,25,5l would give an arithmetic
93.22" of g- (7 + 13 + 19 + 25 +31) or 19 which would
carry a deeper significance than the mere addition and
division by 5. For an A.P., its arithmetic mean is
always a median’: the 'middle' number in the proper
sense of the word. For example, the '19' above is mid-way
between"7' and '51', between.'15' and '25' etc. Unfor-
tunately, the 'mean' has been generalized to include
results obtained from applying the algorithm 1
311- (a:L + a2 + a3 + ... + an) on _a_ny set of numbers
{a1} , not just A.P., and thus the 'mean value' gets
considerably distorted from the 'median value'. In this
writer's opinion, the best way to introduce mean-values
or averages to children is to use examples from Arithmetical
Progression, so that the children may see the ideas behind
its algorithm.
148
Watching the children playing this 'circular track'
game was enjoyable. Two children, A and B, used two
pennies to play the game and they were very excited
whenever bonus points or penalties were about to come up.
B won when he was 'home' in 55 moves. He was obviously
lucky: he got four consecutive heads twice and four
consecutive tails once out of 55 throws, while the
theoretical probability for getting four consecutive
heads or tails is only 1/16. The chronological movements
of A's and B's counters are shown in Table 4.10 (The
integers in this Table refer to the positions of the
counters on the circular track.)
S0 A lost the game by 56-52 or 4 points. Out of
the 55 tosses, B got 18 heads and 17 tails, both of which
were remarkably close to the theoretical result of a
perfect coin. It should be noticed that both B and A
suffered the penalty of (~12) points once in their 55
tosses. The theoretical probability” of getting this
penalty is (1/2)6 or 1/64, but neither the number of
throws nor the size of the circular chart was big enough
to test this theoretical value. So this experience
should be taken as a means to introduce and utilize
negative numbers’ more than anything else. The writer
also questioned the children why they gave 6 bonus points
for '4 heads' and only 5 bonus points for '4 tails'. They
replied that they just wanted two different methods of
149
Table 4.10. Chronological results of a two-player
game using the circular track in Figure 4.9; the
integers shown in boxes refer to either bonuses
(if increasing) or penalties (if decreasing).
H T H T
4 1 1 2
5 2 ; F€%I
{its 3 e : s:
:12: 8 I 9'
“{Z' 1? it:
I I I
:20: F72”: L_1_J
:21: m :2:
Li?" 1 £19.: F3:
12 5 I
{141 r--. I13:
I 15 ' | 17 | :16_:
:16: :18! ~-
L22] 25 :19:
25 24 |_2.§__| 26
26 27 27
28 29 28 29
32 30 31 30
31 32
33 34
35 36
No. of
tosses 2O 15 18 17
jumping on the circular track. Although they learned
earlier that the chance for getting 4 heads is the same
as that of getting 4 tails, the two different bonus systems
should bring home the truth that equal chances do not
always bring equal rewards in real life.
150
Another boy in this group was playing by himself on
'championship': he was tossing a coin to find out the
semi-finalists, the pair of finalists, and the champion
from 8 competitors or 8 teams. His arrangement was
simple: the 8 competitors or teams were grouped arbitrarily
into gpppupggpg,’ and he flipped the coin 4 times to get
the 4 winners or winning teams of the first round. These
were again grouped arbitrarily into two pairs, and he
tossed his coin twice to select the finalists. He then
flipped the coin.for the last time to choose the champion.
The process of successive elimination’ was something like
the following diagram:
A
B A
C A
D D
E A
F E
G G
H G
It should be pointed out to the child that the above
method of elimination is unfair, although such method
is actually used in many tournaments, and also in selecting
candidates for political offices. The transitive.lgg”
does not hold when one discusses human ability. There
have been numerous counter-examples” taken from tennis
or chess tournaments, or any fields of human activities
whose records showed that A beat B, B beat C and yet C
beat A (if C was allowed to challenge A.) A fairer
151
arrangement is to have each competitor playing against
all the rest, one by one. Two points will be awarded
for winning, one point for a draw, and none for losing.
For 8 competitors, there will be 802: gi—E = 28 games
altogether in the first round and the maximum points
earned = 2(8-1) = 14. There may not be a second round
if only one competitor gets the higpest 172121”. (Here
the highest total need not be the maximum score of 14,
because there might be some draws.) This is another
instance of using mathematics to create a fairer situation
to all concerned. It also provides the best motivation
to learn the Combination formula”
The n02 method has another advantage: it can be
used for _a_ny number 93; competitors,” while the child's
method of elimination described above can be used con-
veniently only for 8,16,52, or generally 2]: competitors.
This discussion brings to a close the major types
of mathematical behaviors that arose, or could have
arisen, from the Dice Design Unit during the observed
period (September 25-November 27, 1972).
Conclusion: Despite the name 'Dice Design Unit,‘
the activities undertaken by the observed children were
far from designing a die, or even playing with the usual
6-sided commercial dice. They spent almost the whole
152
term investigating problems concerning the amplest 'die':
the coins They also extended the game of coin-tossing
to include drawing straws and choosing hands, and then
generalized the head/tail concept into a pair of equally
likely events. Some forty mathematical behaviors arose
naturally from the children's determined effort to answer
such demanding questions as:
-- how to devise an effective method of tallying
H and T so that anyone could quickly and conveniently
count them up afterwards,
-- how to graph the results,
-- how to devise an enjoyable horserace type of game
to be played in conjunction with coinptossing.
The above implied that a great deal of mathematical
learning occurred around the themes of Probability and
Graph, both of which had been termed 'basic' or 'unifying'
themes by the National Council of Teachers of Mathematics.
The Council's 24th Yearbook (1959) presented a list of
seven “most basic mathematical themes which should be
central to the entirety of a modern mathematical curriculum."1
The word 'entirety' was later elaborated to mean ”recurring
and varied contact with these fundamental concepts and
processes so that understanding might grow within children
throughout their school careers." Two years later, the
ls.c.r.n., "Growth of Mathematical Ideas, Grades K-l2,"
24th Yearbook, 1959, pp. vi and 2.
153
N.C.T.M. issued an important pamphlet,l
stressing ten
"unifying themes" for teaching modern mathematics. On
both occasions, Graph and Probability were included in
the list. By introducing Graph and Probability in an
activity-oriented atmosphere, this USMES unit is a
positive step towards the idealism deliberated by the
N.C.T.M.
Some people may doubt the real value of such intui-
tive ideas on Probability as introduced by this USMES
unit, but William Feller,2 an experienced teacher in
this field, gave the assurance that intuition would
serve as background knowledge and guide towards deeper
theory and more sophisticated applications.
These USMES children had another advantage over the
children who learned Grade 5 mathematics in.a traditional
class: the former had the first-hand experience in
recording an experiment (by tallying) and counting before
they performed any piece of the resulting arithmetical
work. Such arithmetical problems immediately became
more relevant and meaningful: they were‘ppp just
another sheet of paper, full of numbers, to be handed to
the teacher aide who would grade it the next day, and to
be cast away soon after that.
1N.C.T.M., "The Revolution in School Mathematics,"
A report of regional orientation conferences in mathematics,
1961, p. 22.
2Feller, William, "An Introduction to Probability
Theory and Its Applications," New York, John Wiley and
Son, 1968, p. 20
154
Professor Lomon and Mrs. Beck1
ably described
four kinds of coin-games most suitable for this Unit.
It had been a real concern of this writer that the
teacher might have taken the USMES Manual like a cookébook,
and just prescribed the 4 games to her class, but fortunately
this did not happen. In fact the children of the observed
class had ample opportunity to show originality, from
creating ingenious tallying methods to constructing
circular horserace track on tri-walls, so long as such
originality did not involve gambling with money.
The Wexford group concentrated on learning Graphs,
Probability and other derivable mathematics from coin-
games. The writer was informed that, in the following
term, the children would have the opportunity to construct
and play initially with the cube, the tetrahedron, and
the icosahedron, in response to the challenge: "How
would you design dice for 5, 4 and 5 players?" Some
'Dice Design' groups2 elsewhere did begin the unit by
building regular polyhedra from precut polygons. This
is also a healthy approach. The children in such classes
1Lomon, Earl and Beck, Betty, "Coin Games," usrms
Working Peppy Serial No. D10, 1972, p. 1-18.
2Take, for example, the 'Dice' group at Champaign,
Illinois. The teacher introduced two cubes and a dodeca-
hedron.as early as the second class meeting. Scarcely
had the third meeting started when the children were on
tgziway to construct various polyhedra and test their
rness .
155
will.have some valuable first-hand experience about the
space of 5 dimensions (particularly space perception).
They can also get familar with various terminologies
and concepts in Solid Geometry such as, the angle
between two plgpgg (faces), the intersection between
two planes (i.e. an edge of the polyhedron), the altitude
of a tetrahedron, etc. The precut polygons themselves
offer many valuable theorems in plane geometry.
Throughout the history of mathematics education,
the 'Dice Design' unit is probably the first practicable
blueprint bringing together two divergent disciplines:
5D Geometry and Probability. But, on reflection, one
would see that both disciplines really represent different
parts of man's efforts to study Nature as a whole. It
would be apt to close the Case-Study of this Unit with
the following lines:
"All Nature is but Art, unknown to thee,
All Chance, Direction, which thou canst not see..."
Alexander Pope (1688-1744)
156
The CASE-STUDY of the "Designing for Human Proportion" Unit,
Observed at Pleasant View School, Lansing, Michigan
October 5 - November 50, 1972
I. The behaviors to be observed would focus on the use of
numbers to describe a human body in contrast to the use
of such vague terms as fat/skinny, tall/short, etc.
Children's involvement with these numbers would, hOpefully,
not be confined to arithmetical work on “word-problems“
about body measurements, but would also include the actual
experience of measuring (not excluding the discussion on
the accuracy of measurements); the recording and tabulating
of data; graphing and the calculation of the mean, median,
mode and range; extensive applications to the designing
of clothing, furniture and house fixtures; application to
Graphic Art, especially the drawing of a human face. A
small group of children here posed another branch of
challenge: "What is inside a human body?" which would
lead to an elementary study on anatomy.
II. Brief Description of the 'Human Proportion' Group:
Fourteen 5th graders left their usual classroom every
Tuesday and Thursday (1:50 - 2:45 p.m.)_to work on USMES
in the School Library. Measuring tapes, strings, yard-
sticks, foot-rules were provided for the class. The
library had a beautiful carpet and children found it most
convenient to work on the floor, because the measuring
activities often involve kneeling down, sitting on the
floor with their backs against the wall, or even lying flat
157
on the floor. The round tables (seating 5 or 6 children)
in the library were most useful, because children, while
graphing and drawing pictures, could compare each other's
work and get immediate feedback. The library also cone
tained many things worth measuring and comparing with the
children's own heights, for examples, book-shelves, coat-
racks, drinking fountains, slide-projectors, film-loop
projectors, etc. Geographical globes were there to
provide a case for measuring on a curved surface. Ency-
clopedias were available for the small group interested
in simple aspects of human anatomy.
All the children were in the traditional Grade 5 level
of mathematics and science. No reading nor communication
problem was observed.
158
Activity 1: Usinggnumbers to describe people;
Measuring children's bodies with specific purposes such
as making garments, and desigpipg furniture and other
things for children's use:
The teacher posed the following set of questions to
the class: "How can your mother or a tailor make garments
to fit you? How can a carpenter make chairs, desks and
other furniture to suit children of your size? How can the
shoe-factories manage to produce shoes thatwill somehow
fit most children?" The answers to all these questions led
the children to the conclusion that measuring’ various parts
of a human body‘gp a very useful and essential activity of
life. They seemed eager to have the experience and practice
of measuring people, because they felt that qualitative
terms like 'tall/short', 'fat/skinny', etc. were not
adequate for many purposes, especially to answer the above
questions. Measuring would provide them with gpantitative
9233? to work on. They could then use numbers’ to describe
people, e.g. "He is a 180 lb. man," instead of "He is fat."
Three or four measuring tapes were then passed along,
and the children merrily measured each other in small
groups. The teacher warned the class about two things:
Throughout this Case-Study, the words underlined and
followed py,’ refer to the mathematical behaviors otserved
a group, while those marked ” refer to the potential
mathematical tapics that could have been discussed.
159
first, each group should measure with a specific purpose,
and secondly, the accuracy’ of each measurement should be
checked by at least one of the peers in the group. The
children then organized themselves into 5 groups: the
first group pretended to be tailors, and shoe-makers,
(but one girl did produce a pair of sandals from tri-wall
and strings); the second group pretended to be carpenters,
and the third group to be builders who planned facilities
for a new elementary school, e.g. drinking fountains,
bathproom basins, coat-racks, etc.
1. The Garment Grppp: After some discussion, the
group decided to concentrate first on.measuring and checking
the accuracy of each measurement. It was hoped that they
would be provided with needles, thread, and inexpensive
material later on to try out their measurements like a
real tailor. A girl said she would definitely learn how
to use the sewing machine afterwards. Each person in the
group then fetched a piece of paper and was responsible
for recording’ his or her own‘ggpg’obtained from tape-
measurements. These would-be tailors seriously measured
the parts of their peers' bodies and checked the data
before recording. Most children in the group included
the following measurements’: collar size (which is slightly
bigger than the measurement round the neck); width of
shoulders (distance from left shoulder to right shoulder);
arm-length; breast size or chest size; width and length
of the back; waist size; hip size; pants length; skirt
160
length or dress length; length and width of feet; depth
of a shoe.
At first they wanted to measure to the nearest 1(8 of
ppflpppp,’ but this high degree of accuracy only resulted
in too many arguements and the standard had to be relaxed
down to the nearest pplgflépgp,’ Little did the children
realize that they were measuring curved length’ when‘ppp
pppyg’ itself was only defined vaguely. This was particularly
true when.measuring hip sizes and waist sizes. Watching
these children measuring each other made the writer realize
that a tailor's measuring never involved straight-line
measurements, and the children here were quite realistic
about it. For example, the length of the pants leg has
to be longer than the distance between heel and waist,
measured by two marks on a vertical wall. The distance
between the marks on the wall would give.g straight-line
measurement, M £3, py Euclid's pips; ppstulate,
shortest,’ and hence no allowance would be made for the
movement and bending of the knee.
This activity gave the children an opportunity missed
by most children in a traditional 'math' class: the measuring
of curved distance. Too many 'word-problems' in arithmetic
provide measurements which.involve only straight lines.
It was not surprising to find a girl in this group trying
to measure her girl-friend's waist size by means of a
straigpt ruler. Her method was ingenious, though.
161
2nd Starting
Pt' Contour of
lst the waist
Starting
Pt.
Pt. 0
contact The a?
ruler
Figure 4.11: {Measuring a curve by means of a
straight-edge ruler.
She started with one end of the ruler on her friend's
left side and gradually swung the ruler round the waist,
making sure that the ruler was always a tangent"ppuppg
m. The ppligp 2; contact’ was, in this case, a
variable ppgpp, varying along the length of the curve as
well as the length of the ruler. The last point of contact
(the point at the other end of the ruler) became the
second starting‘ppgpp’ in order to continue the measuring
along the curve. She completed her measuring when the
ruler finally swung back to the first starting point on
the left side. Her result (12 + 4% inches) came remarkably
close to the tape-measured result (17 inches), although
she complained that the ruler slipped too easily and too
often. This activity should give the students a concrete
experience on.tangency to a curve, and the "envelope"’
outlined by a set of (variable) lines. The activity of
curve-stitching (using needlework to envelope line-conics
like the arabola, ellipse and pyperbola”) as suggested by
14
12
10
162
both the Schools Council of U. K.1 and the National Council
of Teachers of Mathematics2 could have been introduced at
this point. Figure 4.12 below shows the simple stitches
outlining the line—conics” parabola and hyperbola.
23 22 21 2o 19 18 17 16 15 14 13
o l 2 3 4 5 6 7 8 9 10 ll 12
O l 2 5 4
16 1718 19 20 21 22 23
1514 13 12 ll 10 9 8 7 6 5
AIIIV
‘lil'
4"
4‘IF'
4'
4"
i.
-.
I'I1g’
:’
'f'
‘
{‘m-
i"
\
‘
‘\\‘- _
\
Figure 4.12: The line-comics parabola and
hyperbola.
1Schools Council: "Mathematics in Primary Schools,"
London: H. M. Stationary Office, 1965, p. 85.
T. M., "Multisensory Aids in the Teaching of
O G.
Mathematics," 18th Yearbook, 1945, p. 79.
165
The tape-measuring of any curve-length should be
coupled with an important approximation,” which is used
so often in practice. It is to approximate the length
of any curve by those of a series of short chords.” For
examples, in navigation, a set of 'rhumb lines' often
replace part of the great-circle‘gpg” connecting two
sea-ports on a globe, and, in laying a railroad track
around the bend, engineers use a series of gradually
deviating tracks, (each of which is straight but short)
instead of a geometrically curved rail (See Figure 4.15).
A D
A
Figure 4.15: A series of chords approximating
a curve.
The wealth of data generated from the measurements
of this group could have been graphed” to find the
median” for each kind of physical measurement (waist
size, hip size, etc.) or could have been pooled to find
the‘ppgp” for each item. The median or mean would have
provided a profile of an average 5th grader. The pgpgg”
for each item could also be calculated, and within this
range, several sizes of garments would be recommended for
production, with maximum” production on sizes around the
mean. The children might even write to the garment manu-
facturers about their findings because the accuracy of their
tape-measurings had been checked several times.
164
2. The Furniture Group: Each member of this group
undertook to design his own desk and chair, temporarily
ignoring the measurements of the desks and chairs provided
by school. The greatest divergence of opinions seemed to
center on the height’ of the desk; some wanted the desk-top
to be half-wgy’ between eye-level and seat-level, some
wanted it lower, and some higher. There was, however, the
agreement that it could not be too low, otherwise the drawer
might interfere with the knees and thighs. So they learned
the existence’ of a'lpgppwppppd’ for the vertical heigpt’
of the desk-top. The criteria for building one's own chair
were easier to agree on: everyone wanted the height to
be determined by one's‘lgg lengph’ (from.knee to heel),
everyone wanted a deeper seat (than that of a school chair),
and the depth of the seat was to be determined by one's
thi -len h.’ Nearly all children in the group complained
about the seat-back: it was too short. They wanted the
back to be three-fourths’ of each one's trunk-lengp ’
(from.neck to hips). Each student also measured his or
her own arm-len th,’ bent at the elbow at his or her
preferred an le,’ just in case one might be allowed the
luxury of having arm-rests in a classroom chair:
It would be unwise to suggest the calculation of
'pggpg and medians for the data of this group, because
that would result in.a set of desks and chairs comfortable
to nobody, (either too big or too small). But the children
were pointed out that, from the furnituredmanufacturers'
165
point of view, it was the mean or median that determined
the size of their products.
5. The School Design Group: This group started with
an ambitious plan of designing a model for a new elementary
school. They wanted to make scaled models’ for classrooms,
offices, corridors, store-rooms, restrooms, the playground,
trees, etc., and their "lot of land” was a 5 ft. xpgfi ft.’
tri-wall ppppd. They used yardsticks and a steel-tape
measure to determine the length’ and‘gggpp’ of typical
rooms, corridors, the paths and the parking lot outside
the school building. At first they thought of using a
39219: pf _l_:2_, but after measuring the length and width
of a typical classroom (18 ft. x 16 ft.), they decided to
change the scale of the model to 1:100. The height of
the model was approximated by that of the ceiling. They
looked up the USMES "How to” cards and learned to use
simple trigonometpy’ to find the heigpt’ of the ceiling
(8% ft.). This figure was checked by means of a yardstick
plus the custodian's ladder. Most of them seemed to enjoy
the experience of measuring distances’ and working out the
corresponding lengths’ on their model. This involved a
lot of calculations on proportion.’ These were the benefits
derived from this experience, although the model was never
completed. Moreover, this group of children were the only
ones that were exposed to the concept pguppppp’ while the
other groups (the Garment group and the Furniture group)
dealt only with linear measurement.’
166
When the childrenfs interest changed from building a
school model to interior design, they spent the rest of
the time measuring’ various things inside the school:
library shelves, drinking fountains, coat racks, heights
of chalkboard and bulletin boards, dimensions of the work-
bench in.the Design Laboratory, etc. They recorded and '
made suggestions for improvement. For example, their
measurements revealed that the top shelf of the library
was too high even for the tallest child in class (4 ft.
11 inches), and the children recommended that the spaces
between the 5 shelves could be reduced’ by 5 inches at
each level, thereby the top shelf could be lowered by 9
inches. They also said the things used by children should
be at most 5 feet high. This represents the concept of’an
pppppfllgpgp’ which the children saw before, e.g., on road
signs. In fact, the children could have been asked if
they had seen _lpggp M’ written somewhere, and the
children should be able to cite several examples: 45 miles
per hour on.a free-way, 18 years old for voting, 850 for
opening a bank account, etc.
They were surprised to find that the height of the
drinking fountain (2 ft. 2 in.) was much 12:93 phpp’ they
thought. One student said this extra low height might
be designed for the sake of kindergarteners. This led
the whole class into guessing or estimating’ the height of
a typical kindergartener. One girl said jokingly: "I am
167
10 years old, and a kindergartener is 5 years old, or
one-half’ my age. My height is 4 ft. 10 in., and a
kindergartener should be one-half my height, so typically
he is 2 ft. 5 in.--just the right height for the drinking
fountain." Everyone in the class knew that she was only
joking, because the attributes’ 'age' and 'height' were
different. It could have been pointed out that 'height'
is not a linear function” _a_; M (age). However, the
class seriously desired to know whether her estimated
height of a kindergartener was correct or not. So, in
their next Activity, they were going to measure the heights
of a sample population’ taken from the kindergarten classes.
Activity 2: Measuring the heights of a sample
population of kindergarten classes, and graphing the
results:
The measuring instrument was a simple device con-
structed by these 5th graders in the Design Laboratory.
It consists of a graduated’ vertical’ tri-wall board
about 4% ft. high, and a piece of glgp’ cardboard used as
a "height indicator" to be put horizontally’ on top of the
kindergartener's head pp.pigpp.angles’ to the vertical
scale. One boy stood by the vertical board and used
ppgflgg: corner’ of a.hard-bound book to check whether the
cardboard indicator and the vertical triwall were really
perpendicular’ to each other. Further it was agreed that
the kindergarteners could keep their shoes on while being
168
measured, so that the data gathered were really the natural
heights pgpp’ the heights of shoe-heels. (The kindergarteners
were measured with their back leaning against the vertical
scale.) Three volunteers measured the heights of the shoe-
heels as the kindergarteners marched in, five at a time.
They found that the heights of the shoe-heels were roughly
1/2 in. in most cases, and so they were going to subtract’
1/2 in. from every item in the collected data. This should
be good enough because the overall heights were measured
pp _t_h_e_ nearest _1_L2_ ip.’ only. The additional heights due
to hair-styles presented a bigger problem. Some hair-
styles could easily add an inch to the natural height,
and many wanted this, too, to be subtracted from‘ppg
relevant 1.393? in the data, because, these people argued, ‘
the class was primarily interested in designing facilities
like drinking fountains, coat-racks, etc. Other children
disagreed and they wanted to measure "from hair to heel"
whatever type of hair a person might possess, because,
they argued, the data should be accurately describing
people how they really looked at that moment. The class
finally decided to go along with the latter because the
additional height due to one's hair was difficult to
estimate’ in most cases. The children were very thorough
in their measuring and recording: they recorded the names
as well as the heights of the kindergarteners, so that their
data could indeed be used "to describe people," (i.e., to
store data for identification purpose) if so desired.
169
When they presented the data in tabulated form,’ they used
code-names like Al, A2, ... A5, B1, B2 etc. instead of
real names, and the students interested in the Describing
People Unit held the key to these code-names. The children's
recorded data are shown here in Table 4.11.
Table 4.11: The heights measured from a sample
population of kindergarteners.
Group A Group B Group C Group D Group E
#4 5'7%' #1 5'8" #1 5'7%“ #1 5'8" #1 5'4"
2 5'8%" 2 5'7" 2 5'8” 2 5'8" 2 5'10"
5 5'8" 5 5'11%" 5 5'8" 5 5'8" 5 5'7"
4 5'5" 4 5'llfifl 4 5'11" 4 5'6%" 4 5'10“
5 4'0” 1 5 5'9%" 5 5'9" 5 5'8" 5 5'8"
Many mathematical topics could be learned from this
Table. Kindergarteners A5, B1, 02, D1, D2, D5, D5, E5 all
corresponded to height 5'8", and this was a real-life
example of mppyfto-one correspondence.’ The labels A1, A2,
etc. were, in fact, ordered airs,’ the first label being
used for group-identification, and the second label for
individual-identification within a group. This notion
was brought out very clearly when a boy tabulated the above
data as Group 1, Group 2, etc., and named the kindergarteners
(1, l), (1, 2), ... (l, 5), (2, l), (2, 2) etc. He quickly
realized that kindergartener (1, 2) was'ppp the same as
kindergartener (2, l). The class also had a chance to see
170
2 matrix _ip the making’: one student shortened Table 4.11
above into the following matrix from:
Group
Individual\\\\\
123%" 3'8" 3%" 3'8" 3'4"
3'8h" 3'7" 5'8" 5'8" 3'10"
5'8” 5'1115" 5'8" 5'8" 3'7"
3'5" 3'11”" 3'11" 3'86" 3'10"
4-0" 394" 3'9" 5'8" 3'8"
A B C D E
\I'I'PUJNH
The sample population were not randomly selected,”
which was a pity. If the procedure of random selection”
were explained to the class beforehand, the children would
certainly have carried this out and learned from the
experience.
It should also be pointed out to the class that the
data in Table 4.11 were projected heigpts”, and not the
curved distance measured by means of a tape from skull
to heel. Instead, a projected height is the distance
between the higpest ppg'lowest points” when.a human figure
is projected’ on to a vertical p;3p_.’ The British model
text on.modern mathematics teaching1 suggested a similar
activity: students lying down on,a large sheet of paper or
lSchools Council (of U.K.), "Mathematics in Primary
Schools,” London, H. M. Stationary Office, 1965, p. 119.
171
cardboard, while the peers nearby drew the contours of
their bodies from heads to heels and then measured the
distance between the two extremities” of each contour on
paper. This is also another way of projecting a human
figure on to a plane, provided the pencil that draws the
contour is always perpendicular” pp'ppphplppg of the paper.
Many measurements, such as widths of the neck, arm, wrist,
waist, hips, etc., could be taken.from this 2D diagpam,”
and checked with the earlier tape-measurements. The immediate
application” seems to be the designing of a comfortable
sleeping-bag for camping, or a comfortable bed.
Next, the teacher asked the children to put the data
of Table 4.11 in,a‘gpgpp.’ The emphasis was that the
children had to think of some methods of graphing by
themselves (without any help from the adults in the class-
room), but the teacher gave the following hint: "The main
idea is to communicate the important aspects about the
numbers in Table 4.11 to other people." After working
for some time, two students came up with the following
graphing methods, which the teacher showed to the whole
class:
172
l. A bar- ra h u side-down showin, the distribution of
heights among the sample population:
3'4" 3'6" 3.8:; - 3.019". 4'
> Lkh
Figure 4.14: Heights shown in a bar-graph.
Apparently this student was interested in tallying
the number 91 people’ against 939;; possible heigpt’ in
Table 4.11. He labeled the various heights in‘gp increasing
sequence’ (5'4", 5'4 ", 5'5", 5'5 ", 5'6", etc.) along a
horizontal line (pgpg’). He wrote an x for each person
tallied, and put the x's beneath the correspondipg’ heights
of those persons. The teacher suggested the graph would
look clearer and better if he put a box around each x. "The
resulting picture is called a‘barsgraph,’" said the teacher,
"and the height (5'8") corresponding to the longest column
is called the‘ppgp.’" In fact, the median” could have
been read directly, and the concept of Normal Distribution”
could have been discussed. One girl, interested in coat-
rack design for kindergarteners, proceeded to calculate the
175
“average" (pepp’) of the data in Table 4.11. She did not
merely add up the 25 items and divide; instead she used
the distributive £9.33 and wrote:
9 persons of height 5'8" : 27'72"
2 persons from each of the groups
5'7". 5'716". 5'10". 5'11”"; ,
Twice 12'56" : 24'72"
1 person from each of the rest;
304:, 3‘5", 3'6”", 5'8””, 509",
5'915". 5'11". 4' : 25'5536"
7619715"
She seemed to have some trouble with lppg division’
(the divisor being 25). The writer asked her to think of
the exchange of Quarters ippp pennies.’ She said 5 quarters
=75 pennies, and sofigspggflgfiplrppiiyp’ and the
remainder’ = l.
25 ) 76' 19226"
5. one
The writer watched carefully to see whether she made the
usual mistake in the next stage by forgetting the remainder l .
But she avoided the mistake by writing ‘
197%
+ 12
25 1 209%
At this stage, the writer helped her along by saying
1 dollar = 4 quarters = 100 pennies,
and she echoed: 2 dollars = 8 quarters = 200 pennies.
1.6. 8125=25x8=200
174
So 25 could go into 209% eight times, and the remainder=9 ".
The writer gave her further encouragement (B. F. Skinner
would say reinforcement) by saying that it was correct so
far because 9 quarters= 9 x 25 =225 pennies which is beyond
the dividend’ of 209%. She nodded in agreement, but then
she did not know how to combine such a diversity of results
to produce the final answer. In the writer's opinion,
adult assistance was essential at this point, otherwise
she would be so muddled up that she might never reach her
objective and might soon lose all her interest in the
problem. The writer reminded her that her original objective
was to find the pepp’ by dividing’ 76'19716" by 25. This
she accomplished in two stages: the first yielded a
partial answer’ of 5'; the second a partial answer of 8"
with a little "left-over". This left-over was 92 par__t_§
£0,111 pl; 22’, or proportionately’ 19 parts out of 50
(2 x 9% =19), and the writer introduced the notation of a
rational number’, 19/50, to the student. Combining these
partial answers as indicated, the student could now write:
5' and 8" and 19/50 inches,
which, finally, became 3' 8%”.
175
2. A Pictorial Graph or a visual presentation of range and
differences in heights recordgd in Tgple 4.11:
4
.4' Q
5 I 10"
» /\/
A1 A2 A3 A4 A5 Bl 32 B5 B“ B5 ... ... El E2 3 4 5
Figure 4.15: A Pictorial Graph
Apparently the girl who invented this graph was interested
in the chronological’ presentation of these measurements as
well as visual clarity to see at a glance the differences’
(in the individuals' heights) and the pppgg’. The vertical
pgplg’ on the left helped to achieve this visual clarity.
Nobody would fail to see that there was a difference in
176
heights between, say, A2 and 31’ The range, determined
by the difference in heights between A5 and E1, could be
read directly:
Range=4'0" - 5'4" = 8"
There was one strong criticism about this graph:
the inconsistency’ over the ppgpmp£_heigpt’ in the vertical
‘pypg’. She enlarged the scale between 5' and 4' without
enlarging that between 0 and 5', and so the 5'4" kinder-
gartener looked only about two-thirds’ of 4'-kindergartener,
while the correct proportion’ should be 40":48" or 5:6.
Her emphasis on visual clarity of individual differences
was done at the expense of correct proportional graphing.
This was the sort of ”Chop-off-theébottom" bar-graph
referred to Huffl in his amusing book, and it was used often
in the popular press to give the readers the false impression
of a pig difference’ between pairs of individual bar-graphs.
At this point the teacher formally introduced.ppp¢
graphs’ by distributing reprints of a journal for elementary
school children. The journal was Scholastic Young Citizen,2
Vol. 57, No. 7, October 50, 1972, which contained an article
called 'A healthier me'. This article used a colorful
bar-graph to show the increments’ in life expectation of
1Hurt, Darrell, "How to lie with Statistics," N. Y.:
W. W. Norton.and 00., pp. 62-65.
2Scholastic Youn Citizen is published weekly, from
Septemter tfito ugh ME? IEcIusIve, by Scholastic Magazine,
Inc., McCall St., Dayton, Ohio 45401.
177
mankind from prehistoric time till 1970. (See Figure 4.16)
The children examined this Figure carefully and then each
produced a set of bar-graphs, arranged in ascending‘ppggp’,
from such data as 'the waist sizes of our group', 'the
trunk lengths of our group', etc.
7‘7“
01
£1
“2
O
-——- s»
.5
__.L‘.
eéoam
mgm 0
ages:
QNMLA
H MM
a b c d e f
Figure 4.16: The average life span of mankind has consider-
ably increased since ancient times: a) pro-historic time,
b3 2,000 years ago, Home, c) Middle Ages, England,
d 18th.century, New England, e) 1900, U.S., f) 1970, U.S.
178
Activity 5: Measuringgthe dimensions of a human face
and other facial features in order to draw better pictures:
Nearly all the children in this class liked drawing, and
they wanted to tie this USMES activity with Art, particularly
with the crayon drawing of a human face, which seemed to be
a difficult task for them. They thought that the numerical
description’ of the facial features would perhaps make the
job easier. So they started to collect quantitative gppg’
about the faces of the students in.c1ass. This was an
admirable and enterprising task, especially when it was
initiated by such young students as fifth-graders. Great
maSters in the past (Leonardo di Vinci, Albrecht Durer,
and others) had long advocated the quantitative study of
‘pppgp,proportion” and projections” as prerequisites to
good painting. Durer himself had written four books on
Human Proportion, one of which contained the following
quotation:1
"First, give the figures a rigpt ro ortion” according
to the canon (laws of physio ogy and anatomy), arrange
them orderly,” lay out the outlines, give the effect
of dep y ers ective,”...see that every limb be
made right in.aIE tEe smallest as well as the greatest
things...."
.By means of a tailor's tape, the children measured
each other's facial features in considerable details:
1From "Egg Writingg of Albrecht Durer,” as quoted by
Henrietta Midonick, "The Tieasury of Mathematics," N. Y.,
Philosophical Library, 1965, pp. 545 & 548.
179
‘ppdpp’ and‘gpppp’ of forehead, distances’ between eyes,
distance between an ear and the nearer’ eye, shape and size
of the nose, width of the lips, shape and size of cheeks
and chin, etc.
After gathering these data, the children used the
ppglgflpg‘lpg’ to put all the facial characteristics on
paper and began to draw. Much to their disappointment,
they found that even such a carefully planned method of
drawing produced only distorted pictures, because the tape-
measured distances of various organs on the face were
distances pp p curved surface’, and it seemed geometrically
impossible to project’ a curved distance of a fixed "length"
on to a plppg distance’ of the pppg "length". At this point
the teacher could have pointed out to the class that mathe-
maticians had already discovered that distances are not
invariant” under projective transformations.” A discussion
on Geometgy pp _a_ curved surface”, or even the elementary
aspects of Riemannian Geometpy” could have also been initiated,
because the children were highly enthusiastic about knowing
ppyithey got distorted pictures. One simple but profound
activity would be to measure the distance between any two
cities, the gpgg” of a certain country, etc. on a spherical”
globe, and then compare with the distance, area etc. printed
on a 2D map. The more enthusiastic students might be intro-
duced to stereographic projection” which is the usual
method of transforming a contour” from a sphere” to a plppg”.
180
An easy-to-handle activity-oriented version of stereographic
projection1 is as follows:
Figure 4.17. Stereographic Projection
A piece of vertical” cardboard is fixed gp'contact
‘pgpp” a spherical globe at some point A on the eguatorial
pppyg.” The center” 0 is the theoretical‘pppppup£,projec-
pégp”. B' and C' are imgges” of B and C respectively.
In practice, the theoretical point of projection (inside
the globe) is not essential to locate B' and C'. To draw
the line OBB', a student can use a toothpick, or a small
stick to create a line through B, perpendicular” pg ppg
spherical surface. (All lines perpendicular to the sphere
will go through center 0.) ‘This line, OBB', meets the
vertical board at B'.
1See, for example, Morris Kline: "Mathematics in
Western Culture," N. Y.: Oxford University Press, 1955, p. 152.
181
Two or three examples of pppjecting” points like B
and C on to their images B' and 0' should be sufficient to
convince the children that, when two end-points” 2; _a_ m
(say, the two eye-balls) are transferred from a pppyg surface”
(the human face) to a.plppg” (the paper), distance is not
preserved,” and hence the tape—measured distance between
the two eyes could ppp be used to draw the picture of the
two eyes on a flat sheet of paper.
It was then apparent that the tape-measured data collected
thus far offered very little help in drawing a better picture
of the human face. The teacher then distributed magazine
cuttings that bore photographs showing the front view (not
side view) of human faces. The children examined them,
and, after a long discussion (not without adult input),
they realized that the distances between any two organs on
a face, ,a_s appeared pp php hoto ra h, were really vertically
projected distances.’ (See the definition of "Projected
distance" in Activity 2). So the children decided to measure
projected distances instead. To start with, they could
measure the projected lengths and widths of the faces of
students in class. The vertical scale on triwall board,
invented for Activity 2, was being brought out once again,
but this time the scale was subdivided’ further to allow
readings pp 3133 nearest _lfi _ip.’ Unlike Activity 2, which
measured‘gpgp ground‘lgygl,’ this new activity would involve
the vertical measurement from chin to forehead and horizontal
182
measurement from left ear to right ear, and so two pieces
of cardboard indicators would be required this time. One
cardboard was placed horizontally £11 £1.19. _l_¢_ey_e_l_’ of the chin,
and the other at the level of the top of forehead, and both
cardboards were placed perpendicular"pg,the vertical scale.
The difference’ in heights from ground level gave the
projected length’ of the face. Both the triwall board
(graduated scale) and the two cardboards (indicators) were
then turned around 99_degpees’ in order to measure horizon-
tal distances. The two indicators were vertically’ placed
.111 contact m’ the two ears, and the projected M’ of
the face was read off from the triwall board. (See
Figure 4.18).
l"‘1"'l'*'l"'l"'l"'l" I 1"'l"'l"'l
Scale
I ‘ Triwall
ear—t Head ear Board
indicator-—» indicator
Figure 4.18: How to measure the Projected Width
of a human face.
This activity taught the children many valuable concepts
in‘§plgg.Geometpy’: the two cardboard indicators were
concrete examples of parallel planes’; each plane is per-
pendicular to the triwall scale, and there the children
could see the concept of the perpendicularipy pg 2 planes’;
185
when a cardboard indicator was put in contact with the
outermost ppppp’ of the curved ear, it demonstrated the
concept of tangency’ between 3 29'; ppg p LL‘BJ and,
finally, when the triwall scale and the cardboard indicators
were turned around 90°, the children experienced a concrete
example of a finite rotation.’
The data collected in this Activity are shown in
Table 4.118.
Table 4.11s. Projected lengths and widths of 12
fifth-graders' faces.
Length6677 76666;;
efw AR»
Nth wt;
a. .31.
Width 16.55%4} 4%5555
Once again the median, iii—623;, £993: _a_ng _rppgg” could
have been calculated from each‘pgp” of the above data,
giving part of a 5th grader's physical profile. Other
interesting profiles might also be suggested: how much
soft-drink he consumes a week, how concerned he is about
pollution, etc.
The teacher wanted to compare the size of a child's
face to that of an adult's. So she herself and the writer
of this Case-study took turns to kneel down and let the
children measure the projected lengths and widths of their
faces. The results were:
184
Teacher's face: Length 8 in., width 6% in.,
Writer's face: Length 7 in., width 6%-in.
The measurements taken from the two adults in class gave
the students some idea about the plpgflpppp_p£_gpowth’ of the
human face once the stage of childhood was over.
The projected length and width of a face would help
to fix the boundgpy'ggppg” of a co-ordinate 5339’: ruled
on rough sketches with a view to improving the likeness of
the picture and the subject. The use of a co-ordinate grid
to improve a drawing was going to be the main theme of the
next Activity.
Activity 4: Using the ideas of proportionate enlarge-
ment and co-ordinate grid to draw better pictures of a
human being:
While the teacher distributed the magazine cuttings
bearing the pictures of human beings, she asked everyone
in class to choose a picture one liked best and draw that
picture using anything one is capable of: color pencils,
crayon, water colors, or even oil paint. The emphasis was,
just for once, ppp_on creativity or subjective perception,
but on the degree p£.1ikeness’ between the given picture
and the drawing.
The children seemed to enjoy this period of "USMES Art"
because they drew only the pictures they really liked.
But, despite the intensive effort of everyone, no student
in class could produce a drawing anywhere close to the
185
original photographic picture he had chosen. The big
problem was that things (objects) in the drawing were mostly
pppnpg proportion.’ The children themselves noticed this:
when all the pairs of original pictures and drawings were
placed side by side, the children made the following comments:
--"The girl's face (in one drawing) is too large."
--"The furniture - tables and television sets - look
crooked. The lines should be straight."
--"The man's body is not big enough, compared with
the pack of Pepsi he was carrying."
--"The pants legs look unreal - too long." (This
cutting was an advertisement on fashion.)
--"This (drawn) picture is OK except that the man's
shoes look awfully big."
The teacher then explained that photographic pictures
looked much more realistic than those drawn by free hand
because the camera could capture the correct proportion’
of things as they really were except minor shrinkage’ of
objects further away due to perspectivigy.’ To clarify the
statement about the correct proportion enjoyed by the image
of every object seen in a photograph, she showed the children
two copies of the same photo: one copy was enlarged’ and
was 1%»times as big’ as the other. It was the photograph
of a lO-year-old girl holding a cat, and standing by a table.
On the table there were soda-pop bottles and glasses, a
flower vase, and a solid state radio set. The teacher
pointed out that all the objects appearing in the enlarged
photo were li-times as big, and she asked the students to
186
verify this. The two photos were then passed from one
child to the next, and most children could be observed to
measure at least one item (say, the girl's face) from one
photo and, after multiplyipg’ ph_e_ length py 1%, checked
the length of the corresponding’ item in the—other photo.
One boy measured the length of the girl's face in the smaller
photo and recorded 7/16 in. (His ruler could measure 33 _t_h_e_
nearest lg 3333). He then multiplied’ by means of the
distributive l_a_g’:
(7/16)(1§) = (7/16) + (7/16)(1/2)
= 7/16 + 535/16
= 1016/16 in.
He then measured the corresponding length’ (i.e., the
girl's face) in the larger photo and the result was lO/l6 in.
The usual manipulation pp fraction”:
(7/16)(1§) = (7/16>(3/2) = 21/32
was not observed, and so two topics: (1) the method of
converting a 323% number’ like 1%- into a single rational
number” 5/2, and (ii) the principle of multiplflng _t_wp
rational numbers”
(a/b)(<:/d) = ac/bd
could both have been introduced, because the motivation
was there already. But one interesting mathematical behavior
was observed here: this boy used a geometrical method’ to
determine (7/16)(l/2)= 5%ll6. (See Figure 4.19).
187
A n C B
o 3 T4 7 16
5%
Figure 4.19: How to find (7/16)(l/2) geometrically.
AB was a length, measured 16 units, and AC measured 7 units,
so that 7/16=AC/AB. By the commutative lag},
(7/16)(1/2) = (1/2)(7/16) = 1/2 of AC/AB
=AM/AB, if M is mid-point’ of AC
==53’2/l6, since M is half-way between 5 and 4.
Another girl measured some other things in this pair of
photos. She used a ruler, correct pphppp.nearest 118 in.’,
and measured the side-way length of the table and the height
of the flower vase. Measuring from the smaller photo, she
reported 2" for the table-length and 1+1/8" for the vase-height.
The teacher encouraged her to express the results as 2:8» ,
or 16:9 when both numbers were increased by a factor‘pg'g’.
This is a very good way of introducing the subject of‘pppgg’.
Next, the girl measured the table-length in the enlarged
photo, and she got 5", which was correct, because
2 . (1%)=2 + g of 2)
==2 + l ==5
When she measured the vase-height in the larger photo,
she obtained 1%”, and hastily she expressed the pair of
numbers as a ratio. She wrote
5 : 1% = 12 : 4 + 5, increasing by a factor of 4
= 12 : 7
188
She was now perplexed because she was expecting the answer
of 16:9, since the teacher had said earlier that, in the
larger photo, 211 things (including the table and the vase)
should increase their sizes by the w Lroportion’, and
hence the ratio
table length : vase height
should remain the same. In fact, this student worked out
the ratio 5:1; too hastily before she checked the validity’
of her pg! 29.322." of 1%". The vase-height in the smaller
photo was 1%" (assumed correct), and the writer showed her that
(1%)(19) = (9/8)(3/2) = '27/16 = 1%
and so the theoretical 9993;: predicted’ a height of 1% in.,
not 1%". The student went to fetch a better ruler (which
could measure to the nearest 1/16"), and this time, the
vase-height, did turn out to be 1%" when she ignored the
blurred part in the bottom. So the 3:33;: in her previous
measurement was
1% - fit; = (3/4) - (ll/l6) = (12/16) - (ll/16) = l/l6 in.
The writer comforted her that it was only a small error,
because the relative _e_§__x-_o_p’=l/l6 : 1% a. 1/16 : 27/16 = l : 27,
or 1 part in 27 parts.
No measurement by rulers will ever be perfectly correct,
and most rulers have been graduated to measure up to a certain
degpee p_f_ accurac ,’ say, within l/16 or 1/52 in.
While the children were comparing the enlarged picture
against the original copy, it was the most opportune moment
189
to introduce the subject of Similar Figures” in geometry.
Both rectilinear and curvilinear figures” in the two
photographs were similar to each other. Their linear
measurements” were proportional”, the smaller length
being always 2/5 of "the larger one (since the enlargement
factor=l%). The children would have enjoyed the exciting
discovery that the gr_e_s, measurements” of any two similar
figures above were in the £92151 9;; 4: ”, the smaller surface
being always 4/9 of the larger one.
Next, the teacher introduced the idea of using a
co-ordinatejgrid’ to help towards further improvement of
the drawing of a human face or any still-life. The teacher
asked a boy pp pulp g co-ordinate 5131’ over the smaller
photo. _Eppp square’ in the grid was chosen to be é-"x «in,
and the origin’ (starting point) was, in this case, the
, top-left corner’ of the photo. Drawing such a grid was a
good exercise on drawing parallel’ and perpendicular’ M,
and gave the children a feeling that graph-paper’ had been
invented with a definite purpose. The teacher also asked
another Student to rule a proportionally’ bigger g1_'j._d_ over
the larger photo. This time the length of each side of a
square in the grid was measured (%)(1%), or 5/4 in. Care
had to be taken to put the origins in the top-left corners
in both cases, otherwise a contour’ inside one set of
squares’ in the smaller grid would not be similar 53’
the contour inside the corresponding set’ of squares in the
190
larger grid. When both grids were done, the two ruled
photos were passed on to the children who obviously seemed
to enjoy tracing similar contours on corresponding sets of
squares in the two grids. The children themselves later
deduced’ that this was a‘pyptematic‘pgy’ of improving the
drawing of a human face when a ruled photograph or even a
(ruled) rough-sketch of the subject was available.
In the next period, students brought old photographs,
magazine cuttings, and rough sketches into the classroom
and ruled a co-ordinate grid over the original picture,
using the intercept-distance’ of either 1/4 in. or 1/2 in.
between parallel lines. They then drew enlarged pictures
of the original copies on graph-paper’ whose squares were
0!
é- x '5'" each. Those who drew from ruled photos did not
seem to have good results, because the photo-paper was often
bent (curved) while the graph-paper was perfectly flat.
This was, once again, the problem arising from the ppgpg—
formation’ of a.ppp.p£_points’ from a curved surface’ onto
a.plpp_.’i
This last activity was one of the best ways to lead
to the formal introduction of the Cartesian Co-ordinate
System.” While drawing a contour or a curve which covered
many squares in the co-ordinate grid, the children would
soon sense the difficulty of keeping‘ppppk’ and counting’
the correct numberlpg'sguares’ involved. Sooner or later
they would discover that an easier way was to select certain
191
kpyrpositions’ on the contour or curve in the original copy
and to draw on the graph paper by jpining’ together~ppp_
points corresponding to those key positions. Once a pair
of mutually perpendicular’ Co-ordinate Agpg’ was set up,
these key positions would be easily identified by an ordered
‘pgipf (x,y), where x and y referred to the perpendicular
distances’ from the vertical‘pgip’ and horizontal pgip’
respectively. Since any two adjacent pgggg’ of a photograph
are perpendicular, they can serve as the Cartesian Co-ordinate
Axes. The lp£p_vertica1'pggg’ and the bottom horizontal‘pggg’
are strongly recommended so that all points in the picture
are situated in Quadrant I’ of the Co-ordinate Plane.
é
Picture
Origin ‘ I-axis
Figure 4.20: Cartesian Axes defined by two edges
. of a picture.
At this point the gppgflgg Tic-tac-toe” could have
been introduced. After preliminary playing with 2D
Tic-tac-toe, the children should also be encouraged to play
with the 5D version of the game. This is one way of intro-
ducing the concepts of ordered triplets”, and ppppg_mutually
peppendicular‘gggg,” as well as consolidating many general
concepts about co-ordinate systems.
192
This concluded the major types of activities of this
Unit during the observed period from the beginning of
October to the end of November, 1972.
Conclusion: This USMES Unit was originally an off-shoot
of the 'Describing People' Unit, and.a.new branch of challenge
has been established: how to design clothing, comfortable
furniture, household fixtures and other utensils appropriate
to the body size of each age-group. Although this Lansing
school started with the same challenge about designing
clothes, furniture, etc., to fit the physical proportion
of 5th graders, their activities soon branched out into
Graphic Art: how to apply this knowledge about human
proportion to draw better pictures of human faces and full-
size human beings. A small group of children here also
embarked on another branching out into the study of elementary
aspects of physiology and anatomy. This arose from one
boy's inquisitive question: "Since my waist size is different
from Anne's, although we are both 10 years old, do we have
different things (organs) inside our waists?" After some
lengthy search in the library, the children did have a
chance to examine photographs and diagrams of the main
organs in the vicinity of the human waist. With the writer's
help, they managed to draw the following simplified
diagram.
195
‘ I U I 2
Liver *9 j ’ 1 Q'F'mvspleen
A
Stomach ”‘1: ‘ ‘ j,
x
L. Intestine-*- “‘»«~- I
‘1‘ Large
Small Intestine- ‘\,:&::> _445‘ Intestine
Caecum
Appendix I
To Orifice "'5 ' 1
Figure 4.21. The main organs around the front
waist-line.
It should be noted that there should be more 22;;5‘ of
intestines than displayed in Figure 4.21. The small and
large intestines together measure up to 40 ft., spirally
curled up within an internal volume’ of l x l x‘% cubic feet.
This experience would be reinforced by such activities as
looking at a spiral staircase in some museum, the spring
inside a clock, or the magnified picture of the wiring inside
a transistor. All of them would represent the idea of
saving space whenever a lengthy object is put in spiral
2.92.9.3
The names used in Figure 4.21 were all common names
because it was agreed that the Latin names appearing in
some encyclopedia were too difficult. To the delight of
the writer, this small group of children were observed to
be interested not only in the positions, but also the
194
different functions of these organs. Given enough time for
guided studies in the library, they would have learned and
drawn the entire anatomical set-up of man.in a somewhat
simplified manner: the skeleton, the breathing system,
the circulation system, the muscles, etc. It is still an
open question whether a 5th grader should be allowed to
dissect specimens of animal organs. But a group of 6th
graders at Wexford School, Lansing, did dissect some frog
legs when they became inquisitive about the variable piggp’
of the thigh and calf muscles while moving their legs.
For those children who have learned even the simplified
version of man's anatomical structure, they would find it
an inspiring example of a well-organized society. The
society's work forces on food-production, transportation,
commerce, communications, waste-treating, defense, etc.,
all have their counterparts inside a human body. In many
ways, the organs of a.man function more efficiently than
the corresponding units of a society.
John Dewey once urged people to consider education'pp
growth‘gpggrowth._a_geducation.1 This USMES unit has grown
from "using numbers to describe people," to the designing
of clothing and furniture, to Graphic Drawing, to the study
of simplified anatomy and its social implication. Every stage
of this growth is some tangible motivation for the study of
mathematical, biological and social sciences.
1Dewey, John, "Experience and Education," Ontario:
Collier-McMillan, 1969, p. 56.
195
One observation should be noted about this group of
5th graders. They measured things in inches and feet from
the start, and hence did not experience the gradual evolu-
tion.of "ppippflp£,measurement"’ as suggested by Piaget.1
Piaget advocated the use of a child's body (from shoulder
to feet) as his own "measuring unit" first, before the
formal introduction of commonly acknowledged(but arbitrary)
units like 'foot' and 'meter'. An USMES teacher, Charlotte
2 at Eaton Rapids, Michigan, did take up this Piagetian
Hayes,
idea and encouraged each child to use his body or parts of
the body to be units of measurement. Many delightful
equations’ were consequently noted, for example:
2 lengths of arms = length from toes to chest,
4 times around the foot = once around the thigh.
etc.
This enterprising teacher also suggested a very good way
to introduce the right-angled triangle’, and the‘plppg’
9; _a_ straight 1.193 by using the data collected from human
bodies.3 Each student took measurements of his own.height
(in inches) and weight (in 1bs.). He then drew to scale
1Piaget, Jean, "How Children Form Mathematical Concept,"
Scientific American, Vol. 189, November, 1955, pp. 81-82.
2Hayes, Charlotte, "Teacher' 3 Log, " USMES Workin. Pa er
on."gesigning for Human Proportion,“ Serial No. C6, 1572,
pp. -5-
3Hayes, Charlotte, "Teacher' 8 Log," USMES Working_Paper
on."Describing People," Serial No. C5, 1972, p. 6.
196
a right-angled triangle OAlBl, with
length 0A1: the number of lbs. from weight measurement,
length A131: the number of inches from height measurement.
On the same diagram, other right-angled triangles, such as
OA2B2, CABBS’ etc. were similarly drawn from his peers'
measurements. (See Figure 4.22). The slopes of the pypotenuses‘
obtained would indicate whether a person was relatively fat
or skinny.
A.Height
3'
A2 Weight
3 1
Figure 4.22. The 310pes of the hypotenuses of a series
of right-angled triangles telling the relative
body sizes of people.
Besides learning the interpretation of a graph, the children
here were also introduced to a new way of measuring anglesz'
by means of the ratios BlAl/OAI’ B2A2/OA2 etc. It should
be emphasized to the children that such angular measures
are constantly used in more advanced mathematics, where
they are represented by the symbols P tan-1(B1Al/OA1), etc.,
with P referring to the principal range‘ of values between
197
The CASE-Study of the 'Burglar Alarm Design' Unit
Observed at Pleasant View School, Lansing, Michigan
October 5 - December 5, 1972
And also the Summer Workshop's Afternoon Sessions
(with children participating)
from August 25 to September 1, 1972
I. The Behaviors to be observed would be focused mainly on
the children's participation in settingguplsimple direct-
current circuits (and thereby learning from scratch the basic
concepts of current electricity), in abstracting the relevant
physical objects into symbols or elements of a circuit diagram,
in.making and experimenting with home-made electromagnets
(and hence learning about magnetic forces and magnetic induc-
tion), and, finally, in hookinggup electric alarm-bells to
doors; windows, desks, door-mats, etc. This last activity
would give the children the experience of measuring large
distances, because they wanted to hide the alarm-bell circuits
at obscure places well away from the 'bugged' doors and windows.
II. Brief Description of the Classes Observed: The two
groups at Pleasant View School were 3rd graders and 5th
graders respectively. Both classrooms were very near the
Laboratory which contained all the electrical apparatuses
as well as measuring devices, e.g. yardsticks, and workshop
devices for soldering, metal cutting, wire-bending, etc.
On the average, the USMES period was twice a week: Tuesday
and Thursday, 12:30 to 1:40 p.m., but sometimes an additional
period was arranged for Fridays. The children participating
in the Summer werkshop's afternoon sessions were mostly 5th
or 6th graders from.Wexford School.
If
198
Both teachers at Pleasant View School took part in the
Summer Workshop. One of them is a male teacher who is quite
familiar with all types of electricians' work, and the lady
teacher of the other class was quite good at arranging a
suitable environment for her jrd grade students to learn from
scratch the concepts of electricity and electromagnetism.
No reading nor communication problem.was observed in
these groups of children.
199
Activity 1: Playing with batteries, wires and bulbs;
and learning from scratch the fundamental ideas of current
electricity.
This activity was observed in the 3rd grade class. The
teacher posed the main challenge of this Unit by talking
about thieves' breakings into stores and homes, and asking
the class what could be done to discourage them. Apparently
most children in this class had heard of burglar alarms
(perhaps from television movies), because they suggested
to install such instruments, but, on closer examination,
the teacher realized that, although these children talked
about burglar alarms, few had seen a pggl.one, and fewer
knew (even vaguely) how it worked. The trouble was that
even the few children who had seen a burglar alarm did not
have a chance to see the entire set-up: they had been
exposed to only part of an alarm system (usually, a bell
or a buzzer). So the real challenge of this Unit became:
how to find out the 'mysterious' (hidden) parts of any
burglar alarm system, or, better still, how to construct
an alarm system that would be equally mysterious to outsiders.
The teacher gave the children a hint that an easy-to-make,
and yet effective, alarm was an electric* one. This hint
L
1"Throughout this Case Study, the underlined words marked
‘ refer to the significant topics in Mathematics or Physics
observed in these classes, while those marked " refer to the
pgtential lessons in these two fields.
200
turned out to be a kind of pretest, because the children's
responses revealed a high degree of ignorance about electric
circuits.‘ They had heard of electricipzf; (one boy even
said "lightning‘ is electricity"); they knew they could get
electricity from batteries (dpzflggllg‘) as well as from
wall sockets, but none of them was aware that it required
a complete circuit‘ for electric current‘ to exist. The
children were thus recommended to go and fetch batteries,
copper wires (properly insulated), bulbs, crocodile clips,
etc. from the Laboratories, and they were going to play
'Light up your heart' because one girl said that the bulb
represented the 'heart' of the system, and a few burned
fingers would later testify that the bulb was indeed the
‘heart (regulator) of the system in this case.
It was gratifying to watch children picking up the
ideas about an electric circuit from scratch. Most of
them only knew that somehow the battery could light up a
bulb (e.g. in a torch light). So they began by putting
the bottom of the bulb on the top of the battery, but
nothing happened. One boy said, "Daddy always talks about
'electric wires' and wiring; so let us try a wire." The
addition of a third element (the wire) did not present any
permutation‘ problem, because the children had the intuitive
idea that the wire, being a connection‘, was to be placed
between‘ the battery and the bulb. The first trial:
connecting the bottom of the bulb to the top of the battery
(by means of a wire) produced no result again. But the
201
children could see and did try other combinations‘,
such as:
bottom of bulb connected to bottom of battery,
bottom of bulb connected to curved side of battery,
threaded part of bulb congggted to top of battery
It would be interesting to ask the children _h_9_w_ £9.22" distinct
combinations they could try. Besides, they learned many
ggometricalpidggg‘ from this experience: (1) the battery
was a real-life circular‘pigpp_cylinder which they could 5
see and manipulate, (2) the top part of a bulb was approxi- E
mately a hollow s here,‘ and (3) the wire was topogicallz
equivalent‘ to a straight lipg‘ in their first set of
experiments. In this case the wire was topologicalkz
different‘ from.a.lppp,‘ As a matter of fact, the children
discovered electric current‘ only when one of them abandoned
the straight line and thought of the next element in the
topological hierarchy: the simple closed 23313,‘ or loop.
Once the idea of bending the wire into a loop set in, all
children would in due course experience the sensation of
some unwelcome has}? (on the wire) and a pretty l_i_gh_t‘ (on
the bulb). But it usually took a long time (nearly an hour
for this class) to discover the correct spatial relationship‘
among the battery, the bulb and the wire. Once the bulb
was properly lit up, it meant success as far as learning
to establish a simple electric circuit‘ was concerned.
In fact, most students who learned by discovery had established
a mischievous, though legitimate, circuit before that: the
202
short-circuit‘ obtained by connecting the bottom of the
battery to the threaded part of the bulb while this threaded
part remained‘gg contact‘ with the top of the battery.
It should be noted that this experience was contrary
to all their previous experiences: they had seen Mother
using a wire to connect an electric iron or vacuum-cleaner
to a wall socket, or Father using a wire to connect a lamp
to a switch. But this was the first time something (i.e.
the battery) had to be connected to itself in order to bring
about the phenomena of heat and light mentioned above.
This generated a lively discussion among three students
because they by now suspected that there were really 322
things inside the battery. "The battery is not really
connected to itself, but we Just connect together the two
things inside the battery: one is at the top knob and the
other at the bottom," explained one child. So the concept
of positive gpg,negative,pg;g§‘ began to take shape. Further,
since no heat or light was observed in the events of such
ordinary connections as the connection of two things by a
string, the connection of a dress to a coat-rack by means
of a coat-hanger, etc., this connection between the two
poles of a battery was indeed a special event. Something
happened to the wire, the bulb and the make-up of the
battery itself, and this special "something” was the children's
idea of the abstract concept of an electric current.‘
203
Children also tried to connect the two poles by means
of an ordinary string, a sticky tape, two pencils, etc.,
nothing happened. So the class of insulators‘ began to form.
Besides copper wire, they would later discover that other
metal wires, tin foil and aluminum foil could be used,
giving them the other complementary} set: the set of
conductors‘.
Activity 2: Making a switch from an empty coffee can,
and defining an open or closed circuit hypinsertingpthe switch:
One child suggested to solder together the battery,
the wire-loop, and the bulb to have a permanent light,
but other children objected.
"The battery will soon be run down," said one boy.
"If the light is going to be an alarm," said another
student, "we want it 'ppf‘ only when there is a burglary,
otherwise the light should be flpgg'.‘ We should work out
an automatic switch.‘"
This second remark came exceedingly close to the 29933-
lyipg,principle‘ of the Burglar Alarm circuit: "The whole
thing is one big switch, whether it is mechanical, pptical,
or electromagnetic."“ The idea of a switch.naturally led
to the concept of an.gpgp‘ or closed‘ circuit, and other
relevant terminology like breaking‘ or closing‘.g circuit.
The teacher suggested that the students should 23kg_
a switch themselves by using metal strips cut from an empty
coffee can, and she explained her rationale: "To make a
switch yourself will enable you to see its mechanism‘ in a
204
constructive manner (in contrast to seeing the internal
mechanism of any toy by tearing it into pieces). This is
better than just hooking a commercial switch to your circuit,
because a commercial switch.has everything concealed inside
a case."
The writer could spot many mathematical behaviors from
the children's activities of cutting coffee cans and drawing
up plans for circuit switches. First, the bottom of a can
is a circle.‘ The children used an ordinary can-opener to
remove the bottoms of these cans, and they competed to get
the most perfect circle. Secondly, the side of a can (where
one gets most of the metal) is a gylindrical surface.‘ The
children had to flatten‘ this curved surface into a.plgpgr
figppe‘ in the form of a rectangle‘ after cutting along the
side of the cylinder. A more traditional teacher might
have objected to the deafening sound of children's hammering
the cut cylindrical surfaces into rectangles. The students
then measured‘ and _I_'u_l_e_d_‘ phi rectangular ir_e_a_ into thin
strips‘ and cut accordingly. While they were cutting metal
sheets into strips, it should drive home vividly the concept
of a straight ling} and parallel l_ip_e_g‘. "Hey, you don't
cut it straight. Follow the line," said one boy to his peer.
The teacher advised the children to fold over the sharp
edges (and corners) of each strip, so that it would be safe
to work with these strips later on.
The next job was to make a switch from the metal strips.
The teacher told the class that they had to think and
205
reason 933‘ how a switch might fit into the complex of the
battery, copper wires and the bulb, before deciding on the
mechanism of the switch. Working individually at first,
the children did not meet with much success, and so the
teacher suggested that drawing §_diagram‘ might help to
figure out the (spatial) relationship‘ of the switch to
other things in the complex. The diagramatic representation‘
of a physical situation is indeed mathematical learning:
the students had to abstract all important junctions (here,
the positive and negative poles, the bottom of the bulb)
into geometrical points‘ (shown as 'boxes' in Figure 4.25)
and the connecting wires into topological lgpgg.‘ They
also had to discard irrelevant variables‘ such as length
of the wires, colors of the battery case, shape of the
bulb, etc. To sum up, a diagram is a kind of mathematical
abstraction,‘ showing only relevant factors such as
relative positions,‘ connections‘ and disconnections.‘
On their first attempt to draw the circuit diagram,
the children learned one more thing: a diagram is £123
necessarily the photographic copy of a physical phenomenon.
A diagram may reveal some internal or subtle connections
or relationships which the eye cannot see. For example,
it took these children a long time to realize that, in a
simple circuit, the 'wire-loop' connecting the negative
pole to the bulb and the positive pole was, in fact, 2gp
a loop at all, but a topological line. Such a conceptual
scheme for relative ppsitions‘ of the three things implied
206
that, in the diagram to be drawn shortly, the bulb had to
lie between‘ the negative and the positive poles. (See
Figure 4.25) Of course, there had to be a loop somehow,
otherwise it could not be a complete circuit. The 'missing'
link in the diagram was, in fact, the internal connection
via the chemical solution, (represented here by the dotted
line.)
Copper Copper
_ Positive ”ire Bulb I ”ire [Negative
Pole l [ Pole
'- ------------------- Chemical Solution ------- <— --------- _,
Figure 4.25: An abstract diagram showing a simple circuit
without a switch.
It was, at this point, relatively easy to insert a
switch into the above circuit because the students could
operate formally‘ on the diagram by means of pencils and
erasers. The teacher reminded the class that the idea of
a switch was to break or make a complete circuit whenever
one wanted. A girl quickly suggested: "We can break the
circuit anywhere on the 'copper wire' part of the diagram
and insert the switch there." The children by now began
to see the significance of the metal strips out earlier,
as one boy remarked: "When two strips touch‘ each other,
the light is on; but when they are moved apart,‘ the light
is off." The teacher reinforced that the remark was correct,
207
and added that the light is on or off, when the circuit
is said to be M‘ or 922‘.
Discussions later led to the conclusion that one
moveable‘ metal strip touching two 9523‘ Fahnestock clips
would be preferable to two moveable strips. The children
drilled a hole near the mid-point‘ of the metal strip,
put a screw through it to serve as a pivot, and mounted
the metal strip and screw on a tri-wall board. Two
Fahnestock clips were then fixed to touch the ends of the
‘ strip when it looked like a horizontal ;i_1_i_g‘ (i.e.
parallel 12‘ an edge of the board), and this was 'on'.
When the strip was rotated to make an _a_ng_l_g_‘ with the
horizontal line, it was 'off'. (See Figure 4.24).
Metal Fahnestock
+ Strip / Clip
1301. Q” g: r-—-—fi ..
Fahnestock Pivo Bulb Pole
Clip
l
l
i
'- ----------------- Chemical Solution -- — --------
L--
Figure 4.24: A mechanical switch added to the
simple circuit.
Activipy é: Mg a batten-holder.
Another activity related to cutting empty coffee cans
into metal strips was the construction of battery holders.
This was to be accomplished in three stages: (1) obtaining
a wooden block or a tri-wall board of comparable 3553‘ to
208
that of the battery, (ii) nailing a 2" x l" rectangular‘
piece of metal strip to the wooden block or triwall board,
and bending both ends of the strip upwards into half-a~
cylinder‘ to fit the curved 3393‘ of a battery laid
horizontalgy,‘ (This was enough to prevent it to 2232.§£§2f
‘ggy§‘), (iii) fixing something close to the ends of the
battery to prevent it from moving lengphwise.‘
Stage (i) involved the measuring‘ of the length‘ and
diameter‘ of the battery and then the drawing of a rectangle‘
whose dimensions were numerically‘gqul to the measurements
just obtained. This activity also involved the children
in sawing wood or using a saber-saw to cut tri-wall into a
rectangle slightly bigger ppgp‘ the one just drawn.
Stage (ii) involved an estimation‘ of the middle-
portion's length of the battery and the semi-circumference‘
of the cross-section. The bending of a rectangular metal
strip into half-a-cylinder gave the children the unique
experience of making‘g.curved surface‘ in contrast to the
traditional experience of lookipg‘gp_one. Many children
made this curved surface almost three-fourth‘ of a cylinder,
because it seemed to hold the battery better. These
children also experienced the 'springy' reaction‘ of the
curved surface as they pushed the battery down. (See
Figure 4.25s).
In stage (iii), most children made the mistake fixing
only 2513 piece of metal strip (about 5" x )6") pp 535113 angles‘
to the first strip and then bending the ends upwards to stop
209
lengthwise slipping.‘ Sooner or later the ends of this
lengthwise strip would pppgp‘ the positive and negative
poles simultaneously,‘ and a violent short-circuit phenomenon
resulted! (See Figure 4.25b). The children learned their
lesson quickly, though. One boy remarked: "Two separate‘
pieces of metal strips are needed, because one continuous‘
piece does not work." So the children started to nail two
Lpshape metal pieces to the wooden block, the distance‘ between
the two vertical planes‘ being approximately the length of the
battery. Some children achieved the same objective by
removing the middle portion‘ of the lengthwise metal strip
and fixing an extra nail to the now loose metal strip on
the left (See Figure 4.250). They explained: "This is to
disconnect‘ the mischievous 'wire' (lengthwise strip)."
f
n
r I
Nail Wooden Nail Nail Nail
block
(a) (b) (c)
Figure 4.25: A home-made battery-holder;
(a) Viewed from one end,
(b) Side-view, short-circuit phenomenon,
(c) Side-view of the improved model. (Cylindrical
strap in the middle is not shown.)
210
The short circuit mentioned earlier gave the children
a very deep impression of the distinction‘ g£_ppg cardinal
numbers '1' and '2'. ("ONE metal strip was disastrous,
TWO were quite safe," said one child.) All too often
students in a traditional methematics class (including College
students) just verbalize the numbers 1, 2, 5, 4, ... etc.,
without having too much impression about 322 events involving
ppggg.numbers.‘ Recently, an Economics professor at Michigan
State University spent a greater part of his lecturing time
analysing meat prices, and one student remarked afterwards:
"It is the first time these weird things called numbers mean
anything to me."
This short-circuit phenomenon also made quite an
impression on children about the difference between a
continuous gppyg‘ (metal strip) and two separate‘ curves
(strips) involving simple discontinuipy.‘
Lastly, the children in this class found out that it
was misleading to look at a commercial battery-holder (without
careful examination of the parts). In,a commercial battery-
holder, the two metal strips touching the top and bottom
of the battery respectively were separated‘ by a very 325p}
rubber strip (an insulator‘) which was barely visible. "This
gives people the wrong impression that it is one piece of
metal there, but in fact they are two pieces," said one
child.
211
Activity 4: Discovering a way_to have a stronger
purrent;_discussing the anatomy of the electric bell; and
windingelectromagnets:
A girl in the 5th grade class wrapped a sticky tape
round the bottom portion of a battery and continued, with
the same tape, to wrap the top part of another battery,
so that the two batteries were joined together with the
positive pole of the second battery touching‘ the negative
pole of the first. It did not take her long to discover
that such a "series" arrangement‘ of two dry cells was an
effective way to provide.§ stronger current‘ to any circuit:
she connected this 'lengthwise‘ combination' (as she called
it) of two batteries to her previous circuit involving a
bulb and a switch, and this arrangement gave her a brighter‘
light than the single battery alone. She was puzzled about
the fact that a commercial battery—holder (which could hold
two batteries) had the batteries laid side by side instead
of joining them lengthwise. It was indeed a good exercise
in topology‘ as well as in ppysics‘ to figure out the
equivalence‘ of the two simple closed curves‘ (current lpppg‘)
in (a) and (b) of Figure 4.26 below:
o 3’
(a) The girl's arrangement' (b) The commercial arrangement
Figure 4.26: Two batteries arranged in series.
212
She went on to join together 5 and 4 batteries 53 series‘
and obtained a brighter and brighter light until the rest
of the class gathered round her desk to see what she had
done. This discovery turned out to be crucial for the whole
class. Before that, several students who had connected
commercial alarm-bells to their circuits tried in vain to
get them to ring, or at best they rang only faintly. "I
have got it:" exclaimed one boy, "we need more batteries:
Since two batteries made the bulb light up pgigg‘ as bright,
they would make the bell ring twice as loud as before."
His statement was not altogether correct; two batteries
would make the electric bell sound as it should, and certainly
not louder than usual. (The commercial electric bells
provided were designed for a potential difference‘ of
5 yplpg,"whil ‘gpgp_battery generated about 1.4 volts only.)
Besides a bulb, a buzzer might be a better current-indicator‘
than a bell.
The class now knew how to set off the electric bell
and in the next ten minutes the whole room was filled with
the ringing noise of electric bells. Soon the children
got interested in the anatomy of the electric bell. This
interest sprang from the request of a boy who wanted to
take apart the different pieces of an alarm bell system,
but the teacher instead advised him to study ppgf pp
electric pgllwgppkg,and then make a buzzer from coffee-can
strips by using the same principle‘ as an electric bell.
213
"What are the parts of an electric bell?" the teacher
asked the class. I see a spring, hooked to a tiny hammer
that strikes the bell," one student responded. "What is
the function of the spring?" asked the teacher. A boy was
observed to take a careful look at the spring and hammer;
he diSplaced‘ the hammer slightly with his finger and the
hammer pgppgflppgk,‘ striking the bell once. (This demon-
strated the gppk‘ done via the potential energy‘ of a Spring.)
The student reported this finding to the class. The teacher
remarked further: "All right, the spring causes‘ the hammer
to swing back whenever the latter is displaced, but what
caused the displacement‘ of the hammer in the first place?
Surely we are not going to use our fingers every time."
This was a timely remark because it made the children look
at their electric bells carefully once again. After several
wildly speculative and incorrect statements such as
--"the spring works both ways: it pushes as well as pulls."
--“the hammer strikes the bell too hard, it bounces back."
etc.
finally one boy did spot a valuable lead, though the whole
set-up was still a mystery to him. He asked the teacher:
"Could it be that the thing which looks like a "cotton reel"
(the electromagnet“) attracted‘ the hammer away from the
bell?" The teacher responded in a wise manner: he did
not say 'yes' right away, but, instead, he advised the whole
class to 2552 electromagnets‘ by first winding an.insulated
electric gipg‘ round a nail, a bolt or any piece of iron,
214
and then passing pp electric current‘ through that winding
wire. "If your home-made electromagnets attract metals,"
said the teacher, "then the electromagnet looking like
'a cotton reel' in an alarm bell will certainly attract
the hammer nearby."
This activity of winding electromagnets offered many
relevant mathematical learnings about circular cylinders‘
and spirals‘. First, if the iron bolt was treated as a
right circular cylinder, one complete pppp‘ of the copper
wire = 2n13units, or nearly 5 times the diameter‘ of the
2233‘. The next complete turn represented the beginning of
a circular spiral‘ path, if there was no overlapping‘ with
the first turn. If a fine copper wire (coated with an
insulating chemical) was used, the children could wind an
incredible length‘ of this wire round cylindrical bolt or
nail of about 5 inches long or even shorter. At Roxbury,
Mass., an USMES class managed to wind 29 £933" 32 11933 of
copper wire around a nail, and to add to the excitement,
they measured“pp_the length of the wire before or after
winding. This gave the children two valuable experiences:
(1) a clear-cut view of saving space by means of setting
up a spiral, (ii) the practice of measuring sizeable distances‘.
(The writer has to concede that throughout his school and
College training he has never had a chance to measure any
length greater than 10 feet, nor to play with a wire or
string of any sizeable length.) At this point, the use of
a trundle wheel“ to measure great distances could have been
introduced.
215
This activity could also have been an interesting and
highly relevant exercise on fractions“ and decimals“ as
exhibited in the following sample calculation:
By direct measurement, e.g., by a screw-gauge or even
a ruler, the student should be able to note that
The diameter of the cylinder = 1/4 in.
The length of 1 turn of the wire = (5.14)(l/4)
= .785 in.
To wind 20 ft. of wire, it requires $3§§g or 505.7,
i.e. roughly 506 times. (The quotient 20x12
worked out fully: €8§§a = 20x%§§1000 = giggg9.=:505,7)
' 3
should be
Figure 4.27: Winding an insulated wire round a
cylindrical iron bolt.
If the #26 AWGl
wire is used, and if the turns are
really _t_i-ggfi and closed 332 3933 93323, 506 turns will cover
approximately 5 in. of the length of the cylinder.
Hence the diameter of this fine electric wire==386'in.,
or roughly 1/61 in. This is equivalent to 0.01654 in., or,
1A.W.G. stands for 'American Wire Gauge'. AWG Standard
copper wires (bare and insulated) ran e from #0000 (diameter
0.46 in.) to #40 (diameter 0.0051 in.). See, for example,
Lister, Eugene C. "Electric Circuits and Machines, N. Y.,
MCGraw-H11-1 00., 1966’ p. Sme
216
as an engineer would say, 16.54 pilg“ (l in.= 1,000 mils).
This simple calculation would reveal to the students the
powerful method of mathematical deduction“ from indirect
measurements. Nobody expects a 5th grader to use a
micrometer“ to measure anything which is i3 Eh_e_ 9_I_:_d_e_r_“
‘2; l/61 in., but, by indirect measurements and calculations,
he can, in fact, determine small magnitudes of that order,
or something even smaller. (He can usually measure things
correct to 1/16 of an in. by a ruler and never anything
which is more refined). After the calculation, he could
check the result with standard AWG Tables, which give the
diameter of #26 wire as 15.94 mile.
The small discrepancy of 0.01654-0.01594, or 0.0004 in.,
should not become a source of discouragement for this kind
of calculation, but it should encourage the students to
investigate further into the reasons for this discrepancy:
first, the approximate“ nature of the solenoid“ length
(approximately 5"), the number of turns (approximately 506),
and n = 5.14, and secondly, the imperfect winding (i.e.,
the turns might be less close to each other than appeared
to the eye). Such an investigation would have been a good
exercise in learning Scientific Process“ and systematic
improvement for accuracy“ in measurement. In any case,
the children who went through the above process of calculating
the thickness of #26 wire would have learned at least one
topic: the ppdgpflp£_magnitude“, for 0.01654 in. and 0.01594
in. really belonged to the same order of magnitude, i.e.
217
1.6 x 10"2
in. (in Scientific Notation“). The concepts
of positive“ §pd_negative exponents“ could have been
discussed here in conjunction with topics in which children
were normally interested, e.g., the large distances involved
in space travels. ’
An arithmetical problem, similar to the one described
in this Activity, arose during the USMES Summer Workshop
at Lansing in September 1972. A 5th grade girl wanted to
make an electromagnet out of a 2" nail by winding #26
wire round it. At the request of the writer, she counted
up the number of turns, and she reported 92 turns when she
used up exactly 5 ft. of the #26 wire. The writer then
formulated a 'nice' arithmetic problem for her to think about:
"92 turns of #26 AWG wire wound around a 2 inch nail
measures exactly 5 ft. What is the mean diameter of
the nail?"
This was a 'nice' problem in several respects:
(1) it contained two irrelevant numbers: #26 and 2 inches;
(the girl could spot them immediately, though),
(ii) the word "mean diameter" was used in a practical
sense, not just an 'average' calculated from some fixed algorithm,
(iii) it introduced the child to the important fact that
l turn=21rr ,
(iv) it introduced a simple first degree algebraic equa-
tion, and its solution,
(v) it was a good exercise on decimal fractions,
(vi) the final answer could be verified by means of a ruler.
218
[Solution: 1 turn = 1rd = (5.1416)d=
Hence d=gzigém = 0.124"
Direct measurement gave d==l/8 in.]
5x12
Activipy 2: Experimenting with electromagnets:
After most children had made their own electromagnets
from nails and #26 wire, they connected the ends of the
wire with a battery, and began to play the enjoyable games
of testing which articles could or could not be attracted‘
by these magnets. For many children, the phenomena of
magnetism‘ was not altogether new to them: they had played
with bar magnets or horseshoe magnets before. Many toys
today also utilize the properties of attraction and repulsion
of magnets, although the magnets are often concealed within
the toys. But the following could be observed to be 93!
experience on Magnetism for these 5th graders:
(1) Increasing the strength of an electromagnetjgy
winding more turns of wire around it: The children quantified‘
t_h_e_ strength of their magnet by counting‘ _t_h_e_ number 2;; @-
‘plgpg it could pick up and hold them steady in.mid-air
for some length of time (i.e. by balancing the magnetic
‘gppgg‘ against the gravitational‘ppll‘ on the paper-clips).
Most children's recorded results were almost the same,
plus or minus 1 or 2 paper-clips at most. Table 4,12 below
is a typical result for the circuit consisting of only one
battery:
219
Table 4.12 Showing how the magnetic force depends on
the number of turns of the winding wire.
No. of turns No. of clips suspended
50 9
100 17
150 25
200 33
250 40
500 45
350 59
This result, whether it was graphed‘ or not, showed clearly
that as the number of turns increased during the first
stage of the winding, the magnetic strength also increased '
'gp.g constant 5333‘ equivalent to the weigpt‘ of 8 paper-
clips for every 50 turns of wire. But, after the 200th
turn, there was a decline‘ in the growth-rate‘ of magnetic
strength, and, finally, the magnetic strength itself began
to drop after the 500th turn. The children were very puzzled
by this unexpected decline both in the growth-rate and
in the magnetic strength itself.
At this pOint, a simple (qualitative) explanation based
on.9pp;puggp“ could have been offered to these children
who had already been motivated by the above puzzle. The .
reason was that, as the electrical resistance“ of the wire
gradually increased (1.13.1.1. 39.2 increasing length“), £1.12.
current gradually decreased.“ Since the magnetic strength
depended 2215.9. 93“ the number of turns and the current, a
decline in the growth-rate of the magnetic strength could
be observed if the current began to decline. (This was an
220
example of a function g; two independent variables“).
Finally when the (external) resistance“ due to the wire was
nearly the same as the internal resistance“ of the battery,
the current was drastically Mg“, and the increasing
number of turns could not make up for the loss of magnetic
strength due to the Lap decline“ in the current, and hence
a solenoid pg 529 M‘ or more would pick up less and less
clips than before. (See Table 4.12). The more enthusiastic
students could now experiment with ammeters, voltmeters“ ,
etc., and study the quantitative aspect of Ohm's Law:
E
I:
H+r
Problems based on Ohm's Law are always good exercises on
fractions“ and solving simple algebraic equations“
involli_ng one 93; two unknowns .
(2) A 'paper-clip' egeriment demonstrating the essence
of the Inversed Square Law:
Several children were playing with their electromagnets
in the following way: each moved his electromagnet nearer
and nearer to a paper-clip, until suddenly, under the £939;
25 attraction,‘ the clip jumped towards the tip of the
electromagnet (with about 20 turns of electric wire in
most cases). The writer asked each student to take note
of the distance‘ between the clip and the magnet when the
'jump' took place. "low, M‘ that distance,” said the
writer, ”and test to see how many more turns of wire you
221
would have to wind around the nail-«in order to make the
paperclip jump as before."
”253.33 pp 2551‘ , naturally, " remarked one boy.
“Let us all try it," said the writer.
To their disappointment, the children found that after
doubling the number of turns, the magnets in all cases were
still not strong enough to attract the clips placed twice
as far as previously. Some even tripled‘ the number of
turns, but the paper-clip in each case still failed to jump
as expected. Most children were on the verge of giving up
when the writer suggested the last brute-force attempt:
to increase the number of turns py _a_ $3339; _a_; g'. and if
it still did not work, then nobody would be able to blame
them for changing activities. But, fortunately, it did
work: all their electromagnets had now enough strepgph‘
(wens £93939 to overcome the limitipg frictional
_f_9_l;_c_e_‘ between the clips and the table, and the clips
jumped toward the magnets as expected.
The writer then asked each child to prepare _tw_o_
electromagnets, having either 8 and 72 turns, or 9 and 81
turns, or 10 and 90 turns, and tried out the same experiment
with the 9.91 condition‘ that the distance between the clip
and the 'stronger' magnet (having more turns) was 5 m:
as much as the distance between the clip and the 'weaker'
magnet on the other side. "What is the significance of
these number-pairs like (8,72), (9,81), etc.?" asked the
writer. “The stronger magnet is always having 9 times the
222
strength of the weaker magnet,“ one boy replied, after a
long and deep thought. At this point, the mathematical
function‘
8 = 9W
(3 stands for 'Strong' , and W for 'Weak'), or generally
y = 9x could have been introduced.
The children carried out the suggested experiment.
They found that , when only one magnet was used, there was
always a critical m: for the stronger magnet was always
5 times that of the weaker magnet. When both magnets were
simultaneously placed on the two sides of only one clip,
and if critical distances were used in both cases, then the
clip would not move: it was _ip eguilibrium‘ under tw0
mg; 3333 opppsite £33333) Only two boys out of the
whole group achieved this spectacular equilibrium, or
balanc ‘, which was a very difficult task to manipulate.
The writer introduced the following two columns to
the children:
If you increase the then you have to
distance between clip increase the strength
and magnet by of magnet by
2-fold 4-fold
5-fold 9-fold
Unfortunately most children in this group were not
accustomed to thinking of 4 as 22 and 9 as 52, and so no
225
mathematical relationship evolved from this experiment, nor
was there any sign of awareness about its implication of
a very important law of Physics. The writer did not draw
any conclusion from the above two columns, nor did he
attempt to verbalize the Inversed Square £92“ Hopefully,
one day in the future, when some High School teacher teaches
these children Physics verbally, they might recall this
earlier experience and learn the Inversed Square Law in a
more meaningful way than those who have not been exposed
to this experience.
(5) The phenomenon of mqgetic induction:
In Experience (1) described earlier, the children had
the opportunity to see a great number of paper-clips (See
Table 4.12) being suspended by an electromagnet. 0n
closer look, the children realised that most clips did not
cling to the magnet directly, but they clung, instead, to
other clips which were nearer to the magnet. It could have
been pointed out to the children that the m: clips really
became temmrqu W‘ ‘ and this phenomenon was known as
Lagetic induction“. Several children here‘b discovered that,
if these clips remained in contact with an electromagnet for
a length of time, they could retain a certain £93293. q;
Lagetizstion‘ even) after leaving the electromagnet.
Incidentally, an electromagnet with several layers of
Paper-clips clung to it was an effective instrument to
study spatial relationshi ,“ especially such concepts as
innermost or outermost elements“, something lying My
224
within“ something else, volume“ and surface area“, etc.
Activity 6: Connecting alarm-bell circuits to doors,
windowsI desk-drawers, door-mats, etc.
Apparently most children in these two classes knew by
now how an alarm circuit could be set up, and so the next
job was to connect these alarm-bell circuits to doors, win-
dows, etc. to achieve the original objective of preventing
burglary. The children spent a great deal of time on this
Activity, but some were quite successful even in their
first or second attempt. The more successful ones are
described as follows:
(i) The 'positive' and 'negative' terminals‘ (i.e. the
two sides of the circuit switch) were connected to two tin-
foils (conductors) separated only by a thin piece of card-
board (insulator). A tight string tied the cardboard to a
(closed) door or window. As the door or window was forced .
open, the string pulled the cardboard away from the tinfoils
whose contact M‘ 3:33 circuit‘ and set forth the alarm.
(ii) Several children made use of the _sp_ri_pg‘ in a
clothespin to ensure the contact of the tin-foils when the
insulator (e.g. a cardboard) was pulled away by the door
or window. Two pg; copper wires could be used in place
of tinfoils in this case: the wires were wound round each
side of the jaws of the clothespin, and the insulator was
inserted in-between. The electrical principle employed
here was exactly like (i) above.
225
(iii) A group of students out out a 2 ft. x 1 ft.
triwall board and labeled it 'Welcome Mat. ' Four springs
were fixed at the four corners of the mat. A large sheet
of tinfoil (about 1-1/2 ft. x 5/4 ft.) was nailed to the
bottom side of the mat, and it was secretly connected to
the 'positive' terminal of an alarm-bell circuit. When the
mat was placed on a floor, the 4 springs held it up (about
1" above ground level). A second tinfoil, connected to
the 'negative' terminal of the same alarm-bell circuit,
was placed on the floor imediately underneath the mat,
and thus was separated from the first tinfoil by 1325 312
ll. When somebody stepped on the mat, the springs were
depressed, the mat was lowered, and the two tinfoils came
into contact, setting off the alarm.
Activity 6 was, indeed, a sort of climax of the
Burglar Alarm Design Unit. It partially answered the
Unit's main challenge about designing a burglar alarm
which would give effective warning. It also brought
together all the physics learned in previous activities,
especially Activities 1, 2 and 4.
The children in one class agreed that it was a good
idea to have the bell or buzzer hidden well away from the
doors, windows and the 'Welcome Mat' which were "bugged.“
So a considerable M‘ of wire was to be used. The
children tried to do a bit of 'advance planning' : they,
by a means of a steel tape measure or a yard stick,
measured‘ the distance between the door. or window to the
226
obscure corner of the room where the alarm-bell circuit
was hidden. Many students forgot 3:3 W‘ _t_h_e_ measured
distances (for the purpose of wir ‘ 3 complete circuit)
and so their advance planning was incorrect, e.g., when a
boy came forward and asked the teacher for 14 ft. of
electric wire to hook up his hidden alarm circuit to a
window, he actually needed 28 ft. of wire. This kind of
realistic distant M‘ also gave the children a realistic
sense of the problem of electrical resistance‘ which gradually
M pp‘ to a sizeable magnitude. The current was con-
siderably reduced‘ as judged by the faint ringing of the
bell. (This was a real-life example of inversed proportion‘,
i.e. current 0C 1 ). The children had already
resistance
learned how to remedy this: adding more voltqge‘ by
connecting one or two more batteries (_i_n_ _s_q_z_~_i_._e_s_‘) into
the existing circuit. (See Activity 4).
This concluded the major types of activities of the
Burglar Alarm Design Unit during the observed period from
early October to early December 1972.
Conclusion: It was already implied in the short
description of Activity 6 that, although the main challenge
of the Burglar Alarm Design Unit provided a kind of focusing
point within an otherwise divergent set of activities on
basic electricity and magnetism, opportunities for learning
some forty different topics in Mathematics and Physics arose
mainly from these divergent activities, and fewer appor-
tunities spring from the main challenge itself. The
227
closest analogy was that, although an orchestra conductor
provided directions for focusing on one or more groups of
instruments at a time, the pretty sound of music came from
a divergent set of instruments, and not from the conductor
himself.
All USMES Units have encouraged the _use of real
objects, realistic experiments, real measurements and
actual counting, etc., in teaching mathematics and science.
The Burglar Alarm Design Unit seems to be more so than
other USMES units observed thus far. Teaching children
by means of real objects, and arranging children to have
some real experience before verbalization of any type, are
in fact not now. One and three-quarter centuries ago,
Johann Heinrich Pestalozzi published: How Gertrude '
Teaches Her Children, a classic in the theory of "Natural
Education.” But it should be emphasized that to learn
from real objects does not mean plwing aimlessly with
these objects; sense impression, observation and intuition
should lead naturally to concept-formation, the art of
abstraction and classification, etc. which Pestalozzi
called "the child's developed powers." The following
wordsl were written by Postalozzi himself:
”All instruction...is only the Art of helping Nature
to develop in her own way; and this Art rests
essentially on the relation and harmony between
J’Pestalozzi, Johann B., How Gertrude Teaches Her
Children, (translated by L. E. HoIIand E F. C. Turner),
$acuse: Bardeen, 1900, p. 26.
228
the impressions received by the child and the exact
degree of his developed powers. . It is also necessary
that the beginning and progress (of these impressions)
should keep pace with the beginning and progress of
powers to be developed in the child."
Pestalozzi's practice was followed and greatly
enriched by Johann Friedrich Herbart who augmented
Pestaloszi's Anschauung (intuition due to sense impression
and observation) with association, generalization and the
"method."1 Herbert's "method‘ meant the development of
general principles for dealing with generalized systems,
as well as the applications of existing principles to new
situations. Both Postaloszi and Herbart voiced regrets
at the separation of theory and practice in traditional
teaching.
Those teachers who would like to add some "Modern
Math" flavor to this Unit could easily do so by branching
out into the study of logical circuits involving only a
battery, switches and bulbs. This is probably one of the
best ways of introducing mathematical logic to elementary
school children, because they could check the validity of
each logical statement by practical means. Figure 4.28
below shows how to set up simple circuits for starting
off this new set of activities.
1Dunkel, Harold B., Herbart and Education, New York:
Random House, 1969, pp. ‘75 m 116.
229
___,$ ‘ _3
L1- __[__
(a) (b)
Figure 4.28. The circuits displaying the consequences
of the logical operations p“; pB and p‘v p3.
Statements like "switch A is on" and "switch A is off"
are abbreviated to be PA and.»pA respectively. Various
joint operations upon switches A and B would result in
one of the two possibilities: the light is either pm;
or 93;, written briefly as L, ornL. Sooner or later the
children will be able to abstract the following basic
statements from their practical experience:
(a) p“ p3=91oa (app/x («p3)=>-1a;
(iv-Pfin PB =54“ P‘ A (spa) =$"'L-
Similarly four other basic statements could be attracted
from (b). Usually the children could easily spOt the first
two possibilities and verbalize "Both 'on' means 'on',
and both 'off' means 'off'.‘ The teacher had to step in
at this stage and asked them to think of more possibilities
until all four were exhausted. Many logical games can then
be played, and points are scored by correctly supplying
logical symbols for the question-marks in the following
250
complicated circuits, e.g.
PA
/
fl \
_SL
‘ 9 ‘
rif j «L 7 L ?
fi—J ? PE
[ I I
Figure 4.29. Logical circuits for a kind of guessing
game.
These games can.be made openeended by allowing children
to change freely the logical symbols in the given circuits
into opposites, or better still, to devise new logical
circuits of their own.and play accordingly. The only
important rule is that they must not chest by operating
the switches to get the answers; they should figure out
the answers first before operating the switches to verify
their answers which have been arrived at logically; it thifl
point, the kind of elementary logic advocated by the
Cambridge Conference1 could have been introduced: open
sentences and their true/false solutions, equivalence as a
'double implication,‘ contradictions, indirect proofs, etc.
These tepics were recommended for classes between Grades
4 and 6, depending on their interests and maturity.
1Cambridge Conference Report: Goals for School
Mathematics, Boston: Houghton MifflIE 00., 1963, pp. 51-41.
231
To sum up, although Symbolic Logic can be introduced
here, this USMES Unit is pqp,primarily designed for that
purpose. Instead, it should be viewed as an effective means
to provide children with first-hand experience about many
principles and concepts in mathematics and physics which will,
unfortunately, be presented gymbolicalgy,in the next rung of
the educational ladder. They will soon meet with a sea of
symbols in Junior High Mathematics:1r, sq. rt., m(AB), :5, etc.
plus a wider sea of symbols in Physics:
n for number of turns of a solenoid,
H 1'5? magnetic field,
I Tor'current
E To? voltage
f To? a dry-cell
mm a resistance
SEE.
Hopefully the experience they gain from this Unit will help
to put some vitality into an otherwise boring manipulation
of symbols followed by meaningless calculations. The writer
showed the script of this Case-Study to a personal friend,
an instructor in Psychology. After reading it, he exclaimed:
"What a _n_e_! and revolutionapy way of teaching math and physics:
It's good for the kids, though. If I were taught this way
when I was little, I might have ended up with a Ph.D. in
Physics, and not Psychology like the one I've got." The
writer reflected afterwards: 'revolutionary' was the wrong
word. To put vitality into mathematical symbols has been
252
practiced by good teachers for centuries. The following words
are quoted from one of them, Harold Fawcett:l
"Behind every symbol is an idea. It is the idea
which is important, and it is familiarity with the
idea which puts life in the symbol. It is,
therefore, of the greatest importance that the
idea be developed before it is symbolized, for, to
give a child a symbol for an idea he does not have
is to encourage him to take a long tragic step
toward intellectual disaster."
The same sentiment was also implied by work of another
retired teacher, F. L. Griffin,2 and it can be concluded
that good teaching knows no temporal boundaries.
1Fawcett, Harold P., "Reflection of a Retiring Teacher,"
The Mathematics Teacher, Vol. 57, November 1964, pp. 450-456.
2Griffin, F. L., "Some Teaching Reminiscences," The
American Mathematical Monthly, May, 1969, pp. 460-467.
CHAPTERS
DISCUSSION AN D CONCLUSION
The foregoing description of mathematical behaviors
arising from the four USMES units shared considerable
m (“‘1’-i3 (In?
common ground with the mathematical content for I - 6
proposed by the 1965 Cambridge Conference for School
Mathematics. The following points of similarity between
the asses Units and the Cambridge Report1 are important:
1. The role of‘physical equipment is emphasized.
Whether one thinks in terms of pro-mathematical experience,
or in terms of aids to effective communication, or simply
as attractive objects that increase motivation, the con-
clusion is inescapable that the children can study mathe-
matics more satisfactorily when each child has abundant
opportunity to manipulate suitable objects.
I? . Thai-
2. The bed-rock foundation for elementary mathematics
consists of counting and physical interpretation of fractions;
symmetry and invariant properties of geometrical figures;
real experience in collecting data; use of graphs and other
{land displays of data; and the vocabulary of elementary
o c.
5. Students are encouraged to seek methods for checking
the correctness of their solutions or answers without
recourse to the teacher.
4. Long-range projects undertaken by individual
students or small groups of students are preferred so
that students may have experience with the extended aspects
of mathematical learning involving many types of modeling
and mathematical techniques.
1Cambridge Conference for School Mathematics, "Goals
for git-1:31 Mathematics,” Boston: Houghton Mifflin Co., 1965,
PP- .
235
254
Nevertheless, some mathematical topics recommended by
the Cambridge Conference were not observed in the four USMES
units, for examples,
(a) Arithmetic of signed numbers,
(b) Inequalities and absolute values,
(c) Prime numbers and factoring,
(d) Use of straight-edge and compasses to do geometrical
construction,
(e) Interpolation.
0n the other hand, these USMES children learned many
[FFW-Qe-fmmv “MK-.0196 «an
sophisticated concepts in Probability, Topology and Founda-
tion of Mathematics which were conspicuously absent from
the Cambridge Report. This Case-Study would, hopefully,
help future USMES teachers to locate and utilize the
potential mathematical behaviors inherent in these Units'
activities. No doubt the list of mathematical behaviors
(in Chapter 5) will grow as future groups of USMES teachers
and students discover more and more mathematical topics
in the course of their work.
The writer of this Case-Study fully realized that his
graduate training in Mathematics was a positive asset in
doing this research, because it helped him "to see mathe-
matics in.action” whenever such an opportunity arose.
But he also realized that graduate mathematics alone would
not be sufficient for this work. It required another
component: he had to be interested in the children's
235
development in the cognitive, affective, and psychomotor
domains.
In doing this Case-Study, the focus was on:
1. The integration of several kinds of educational
experiences pertinent to mathematics learning, and the
integration of activity learning with the usual paper-and-
pencil work,
2. The relation of mathematics to some real-life
long-range problems, not just the short-range problems
involving only symbol manipulation,
“ I?
5. Students' opportunity to acquire problem-solving
ability and to learn the scientific method,
4. The mathematical behaviors arising naturally from
these USMES Units or their sub-tasks.
V'
The first three points mentioned above are, in fact,
concurrent with Harold Fawcett's thinking.l He wrote:
"To meet the responsibilities of citizenship, the
mathematics program should be designed to promote
problem-solving process, to define and deal with
problems of concern to the society, to gather
and organize relevant data, to detect underlying
assumptions of the system, and to draw valid
conclusions by both inductive and deductive
reasoning. Mathematical principles should be the
outgrowth of experience rather than the basis of it.
Operational skills should serve a recognized and
useful purpose."
The USMES activities motivate and introduce a student
to certain mathematical ideas, say fraction and percentage,
but it is up to the student to practice more on those topics
if he wants to achieve such.mathematical skills. There are
1Fawcett, Harold P., "Mathematics for Responsible
Citizenship," Mathematics Teacher, Vol. 40, November 1947,
pp. 199-205.
256
students who genuinely like expository teaching to guide
them along in these sub-tasks. Others continue to explore
and discover their own solutions to these sub-challenges.
At this point diversity is desirable. (Eventually the
results of these sub-tasks will be combined to answer the
major challenge.) The most appropriate underlying principle
here seems to be: "Teaching should increase the diversity
of students' achievement rather than the uniformity."1
Conclusion: The following mathematical behaviors were
observed to have permeated throughout all the four USMES
Units here: counting and measuring which lead to meaningful
usage of whole numbers, decimals and fractions; place value;
the four fundamental operations of arithmetic; percentage;
ratio and proportion; estimation; collection and tabulation
of raw data; graphs; proposing hypotheses and testing them;
elementary logic; abstracting concrete situations into
mathematical relations; sets and their elements; ordinal
and cardinal numbers; ordered pairs; simple geometrical
shapes like triangles, rectangles, and circular cylinders.
In addition, the following mathematical behaviors were
observed in the individual units described below:
The 'Soft Drink Design' Unit: Independent and dependent
variables; composite function; multiplicative inverses;
matrices and reduction of the size of a matrix; frequency;
lFitzgerald, William M., "On the Learning of Mathematics
by Children," Mathematics Teacher, Vol. 56, November 1965,
PP. 517-521-
a"
237
,points on the Number Line and transformations of these
points; invariance under a transformation; confounding
variables.
The 'Dice Design' unit: Theoretical probability;
approximations; closure, commutative and distributive
laws; arithmetical mean and progression; the combination
n02; the histogram; the Normal Curve; plane geometry of
the triangle and the hexagon; construction.of polyhedra
from pre-cut polygons; the 'double-entry' principle of
book-keeping; one-one correspondence.
The 'Human Proportion' Unit: Examples of linear and
non-linear functions; curved lengths and curved surfaces;
orthogonally projected heights; rotation; tangency; simple
trigonometry; calculation.of mean, median, mode and range;
many—to-one correspondence, parallel and perpendicular
lines; Cartesian Co-ordinates.
The 'Burglar Alarm Desigp' Unit: Arithmetical deduction
from indirect measurements; scientific notation; inverse
proportion; inverse square law; permutation of five elements;
first difference; spherical surface, a topological line;
simple closed curves; simple discontinuity; separation;
distance between two planes; direct proportion; informational
aspect of cardinal numbers.
The following potential mathematical topics could
have been included: algebraic problems involving one or
two unknowns (Soft Drink and Burglar Alarm Units); sets
P?“
257a
which are topologically equivalent (Soft Drink, Human
Proportion and Burglar Alarm Units); random selection;
stratified sampling (Soft Drink Unit); equality (Soft
Drink, Dice Design Units); relative error (Dice Design,
Human Proportion, Burglar Alarm Units); intersection of
two planes and the angle between them (Dice Design Unit);
envelop and curve-stitching (Human Proportion Unit);
various measures of angles: degree, radian, and tan"1 (y/x)
when referring to principal values (Dice Design, Human
Proportion Units); positive and negative exponents (Burglar
Alarm Unit) and logical circuits (Burglar Alarm Unit.)
This Case-Study could serve as a guideline or recommended
procedure for teaching mathematics in.an.USMES. The list
of potential mathematical topics would help teachers to
initiate mathematical sub-tasks whenever an opportunity
arises, so that these USMES Units might be utilized to
their full potential in generating activities and discussions
which are pertinent to mathematical learning.
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WT-..5~"
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