TF'E’S‘S

w

M

LIBRARY

Michigan $923
Universt)’

W

This is to certify that the

thesis entitled

COMPARING AUDIOVISUAL TO TRADITIONAL
AGRICULTURAL ENGINEERING INSTRUCTION IN BRAZIL

presented by

Mauro Flavio Meza Montalvo

has been accepted towards fulfillment
of the requirements for

Ph . D. degree in AET

 

 

Major professor

 

07839

 

   

a. ,N-
:ix"
r1715” \}'\‘ I

4

A ' \l‘ 5"" ’ |
.;‘l~:‘:;‘\tlzf’?. .-_4'

     
 

 

w:

25¢ per day per 1m

RETURNIM LIBRARY MATERIALS:

Place in book return to move
charge from circulation records

 

COMPARING AUDIOVISUAL TO TRADITIONAL
AGRICULTURAL ENGINEERING INSTRUCTION IN BRAZIL

By

Mauro Flavio Meza Montalvo

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Agricultural Engineering

1980

957

z" /
crvvé

ABSTRACT

COMPARING AUDIOVISUAL TO TRADITIONAL
AGRICULTURAL ENGINEERING INSTRUCTION IN BRAZIL

By

Mauro Flavio Meza Montalvo

A number of factors such as a shortage of teaching personnel,
limited laboratory facilities, too few textbooks, shortage of finances,
and a high number of students with widely divergent backgrounds have
contributed to the need of a search for alternative methods of instruc-
tion in universities in developing countries. It has been suggested
that a change from the traditional lecture model of instruction to
audiovisual, self-instructional modules might overcome a number of
the instructional problems in the teaching of agricultural engineering
subjects.

The present study deals with an investigation into the question
of the relative effectiveness of the audiovisual self-instructional
method as compared to the traditional method in teaching "The Use
of the Moldboard Plow".

TWO studies are actually described in this research; and both
were tested with Brazilian students:

- A Pilot Study
- The Main Study

The pilot study was performed for the following purposes:

a. To compare audiovisual and traditional (lecture)
instruction in terms of student learning and

attitudes;

Mauro Flavio Meza Montalvo

b. To compare differences, if any, in learning
and attitudes between urban and rural univer-
sities;

c. To determine differences, if any, in learning

and attitudes between class size.

The audiovisual treatment consisted of a slide-tape presentation
on the Moldboard Plow developed for American English speaking students
at Michigan State University. The audiotape was recorded in Portuguese
and the presentation was group mode.

The audiovisual and lecture treatment addressed six learning
objectives. On four of the six objectives there were no significant
differences between audiovisual and traditional instruction, nor was
there a significant differences with respect to class size and univer-
sity effect. For two objectives, the traditional instruction was
found to be the better. Therefore, the following were needed: changes
in the audiovisual treatment, reduction of number of objectives, and
simplification of the statistical design.

I The purpose of the main study was to compare a revised audiovisual
module to a traditional lecture on the same topic of the pilot study.
The new module included 54 slides to achieve three objectives with

20 students.

Data from the main study indicated that the audiovisual treatment
was better in terms of student achievement. Student attitudes were

still very favorable to audiovisual instruction. Data on cost indicated

Mauro Flavio Meza Montalvo

that the audiovisual instruction cost less per instructional hour
than lecture.

The results of this study indicated that: (l) audiovisual in-
struction can be more effective than traditional instruction in teach-
ing agricultural engineering topics in Brazil; (2) audiovisual materials,
in order to be effective in developing countries, must be designed
in accordance with a systematic design process, incorporate the seven
characteristics of well-designed instruction, and must include a cross-

cultural adaptation.

APPROVED:

Major Professor

/..~-) / I :&~:;<f/47
,»;qZJ Hake/U/ ”/Y’Cl'i

Department Chairman /

DEDICATION

This thesis is dedicated to

my Father and Mother.

ii

ACKNOWLEDGMENTS

The author wishes to express his appreciation to the many persons
who have made this study meaningful, rewarding, and possible:

Particular thanks are expressed to Dr. Robert H. Wilkinson for
his encouragement and counsel as chairman of the guidance committee.

Special thanks go to Dr. Allan J. Abedor for his guidance, and
most importantly, for increasing my interest in the educational process.

Gratitude is also expressed to Dr. Altir A. M. Correa and Brazi-
lian students without whose cooperation this thesis would not have
been possible.

I would also like to express my appreciation to Dr. Charles Black-
man, and Tom Burkhardt for their insightful suggestions and Ms.
Suatawana for her guidance during the statistical analysis.

My special thanks are given to my wife, Amada, my son, Mauro Jr.,
and my daughters, Patricia and Maria for their patience and encourage-

ment in my ability to complete this task.

iii

TABLE OF CONTENTS

Page
LIST OF TABLES .......................... vi
LIST OF FIGURES ......................... viii
CHAPTER I. INTRODUCTION ..................... 1
CHAPTER II. LITERATURE REVIEW .................. 4
2.1 Traditional Instruction (Lecture Method) ........ 4
2.11 Advantages of the Lecture Method ......... 5
2.l2 Limitations of the Lecture Method ........ 6
2.2 Individualized Audiovisual Self-Instruction ...... 6
2.21 Advantages of Audiovisual Self-Instruction . . 8
2.22 Limitations of Audiovisual Self-Instruction 13
2.3 The Characteristics of Successful, Nell-Designed
Audiovisual Self-Instruction .............. 15
2.31 Evaluation .................... 25
2.32 Testing ..................... 26
2.4 Previous Research Comparing Audiovisual with
Traditional Instruction in the United States ...... 28
2.5 Context of Brazilian Higher Education ......... 32

CHAPTER III. A PILOT STUDY TO COMPARE A PRELIMINARY MODULE TO
AUDIOVISUAL INSTRUCTION WITH TRADITIONAL INSTRUCTION 35

3.1 Purpose of the Study .................. 35
3.2 Design of the Study .................. 36
3.21 Population and Sample .............. 36
3.22 The Evaluation Instrument ............ 38
3.3 Attitudinal Measure .................. 41
3.31 Scoring and Display ............... 43
3.4 Hypotheses ....................... 43
3.5 Design of the Statistical Analysis ........... 44
3.6 Methodology ...................... 47
3.7 Results of the Analysis of the Pilot Study ....... 49
3.8 Results of Attitudinal Measures of the Pilot Module . . 62
3.81 Results of the Open-Ended Questions ....... 66
3.9 Conclusions of the Pilot Study ............. 67

CHAPTER IV. DEVELOPMENT OF THE REVISED AUDIOVISUAL INSTRUCTION
MODULES AND ITS COMPARISON TO TRADITIONAL INSTRUCTION 69

4.1 Revision of the Self-Instructional Audiovisual Module
for Brazilian Students ................. 69

iv

TABLE OF CONTENTS (Continued)
Page
CHAPTER IV. (Continued)

4.11 Inherent Problems of Brazilian Universities . 70
4.12 Characteristics of the Ideal Teaching-Learning

Situation .................. 71
4.13 A Workable Design Process for Developing
Audiovisual Modules ............. 71
4.2 Revision of Module Objective and Test ....... 76
4.21 Revision of the Evaluation Instrument Tests . 77
4.3 Revision of the Statistical Design ......... 79
4.4 Application of the Attitudinal Measure ....... 80
4.5 Determination of the Cost Effectiveness of the
Audiovisual Module ................. 80
4.6 Hypotheses ................. ,. . . . 82
4.7 Design of the Main Study .............. 83
4.71 Population and Sample ............ 83
4.8 Methodology .................... 84
4.81 Procedure .................. 84

CHAPTER V. RESULTS AND DISCUSSION OF THE STATISTICAL ANALYSES 87
5.1 Discussion of Findings Relative to Posttest

Achievement .................... 92
5.2 Results of the Attitudinal Measures ........ 93
5.21 Discussion of the Attitude Survey ...... 93
5.22 Results of the Comments on the Open-ended
Question ................... 97
5.3 Results of Determining Cost Effectiveness of
Audiovisual Instruction .............. 98
CHAPTER VI. CONCLUSIONS AND RECOMMENDATIONS ......... 101
6.1 Conclusions .................... 101
6.2 Recommendations .................. 103
BIBLIOGRAPHY ......................... 104
APPENDICES .......................... 110
Appendix A. Pretest -- and -- Posttest ......... 110
Appendix B. Student Questionnaire ........... 113
Appendix C. Summary of Comments from Open-Ended
Question (Pilot Study) ........... 115
Appendix D. Norksheets' ................. 117
Appendix E. Module 1: Using the Moldboard Plow for
Tillage .................. 122
Appendix F. Summary of Comments from Open-Ended
Questions (Main Study) ........... 136

Table

2-2
2-3
3-1

3-2

3-3
3-4

3-6

3-7

3-9
3-10
3-11

LIST OF TABLES

Traditional vs. individualized instruction methods . . . .
Summary of characteristics of effective instruction
Undergraduate enrollment: 1974 .............

Number of subjects per unit for the treatment versus
university interaction effect ..............

Distribution of test items across the objectives and
weighting ........................

Factors and item numbers of the attitudinal measure
Distribution of class size by group and treatment

Results of testing Hypothesis I on Objective 1 (university
versus treatment .....................

Results of testing Hypothesis II on Objective 1
(traditional versus audiovisual) .............

Mean scores for traditional and audiovisual groups for
all universities .....................

Results of testing Hypothesis III on Objective 1 (treat-
ment versus class size) .................

Mean of variance of class size groups ..........
Scheffé contrasts for class size and type of instruction .

Results of testing Hypothesis I on Objective 2 (university
versus treatment) ....................

Results of testing Hypothesis II on Objective 2 (tradi-
tional versus audiovisual) ................

Mean scores for traditional and audiovisual groups for
all universities .....................

vi

'Page
14

16
33

38

39
42
46

53

53

54

55
55
56

57

57

58

LIST OF TABLES (Continued)
Table Page

3-14 Results of testing Hypothesis III on Objective 2
(treatment versus class size) .............. 59

3-15 Mean scores for class size and type of instruction . . . . 59
3-16 Scheffé contrasts for class size and type of instruction . 60
3-17 Results of testing Objectives 3, 4, 5 and 6 (university
versus treatment, traditional versus audiovisual method,
treatment versus class size) ............... 61
3-18 Results of attitudinal measure of the pilot study . . . . 63

3-19 Results of open-ended item #17 grouped according to the
percentage of frequency ................. 67

4-1 Distribution of the items according to module content
of the objectives .................... 76

4-2 Distribution of the items according to the objectives . . 78
4-3 Distribution of the items according to type of question . 78

4-4 Groups, factors, and item numbers of the attitudinal
measure ......................... 81

5-1 Means and standard deviations of the three objectives
of both traditional and audiovisual instructional

methods ......................... 87
5-2 Results of testing Hypothesis I on Objective 1 (tradi-

tional versus audiovisual) ................ 89
5-3 Results of testing Hypothesis II on Objective 2 (tradi—

tional versus audiovisual) ................ 90
5-4 Results of testing Hypothesis III on Objective 3 (tradi-

tional versus audiovisual) ................ 91
5-5 Results of attitudinal measure, means and standard

deviations (main study) ................. 94
5-6 Development cost for audiovisual instruction ....... 99
5-7 Development cost of traditional instruction ....... lOO

vii

Figure

3-1

3-3

3-4

3-6

3-7

4-1
4-2

5-2

LIST OF FIGURES

Identification of the hypotheses across six objectives . .

Mean performance
Hypothesis II (N

Mean performance
Hypothesis II (N

Mean performance
Hypothesis II (N

Mean performance
Hypothesis II (N

Mean performance
Hypothesis II (N

Mean performance
Hypothesis II (N

by subjects on Objective One,
= 227) .................

by subjects on Objective Two,
= 227) .................

by subjects on Objective Three,
= 227) .................

by subjects on Objective Four,
= 227) .................

by subjects on Objective Five,
= 227) .................

by subjects on Objective Six,
= 227) .................

Range of the attitudinal measure (pilot study) ......

Formative evaluation process ...............

Number of students per class for the instructional

treatment . . .

Mean performance
(N = 120) . . .

by subjects on Objectives 1, 2 and 3

Range results of the attitudinal measure (main study)

viii

Page

64
75

Chapter I
INTRODUCTION

Many universities in developing countries have a decided handicap
in teaching technical subjects such as agricultural mechanization.
These universities suffer from a shortage of teaching personnel,
too few textbooks, inadequate laboratory facilities, shortage of
finances, and a high number of students with widely divergent back-
grounds. These facts were documented in Brazil by an agricultural
engineering survey team report 13 (1976) that worked under Michigan
State University and the Brazil Project. Their recommendations,
based upon these factors, follow:

Encourage and develop some new innovative teaching methods,
such as use of teaching carrels with slides and tapes.

A pilot model might be made for farm machinery and used

to supplement the instructor contact hours. Such a program

is in use at Michigan State University and could be adapted

and translated into Portuguese for use in Brazil.
In addition, they documented a need to:

"require more self-study on the part of the student."
Moreover, the most widely used method of instruction is the lecture,
which, while effective for many subjects, may not be effective for
instruction in highly technical or skill-oriented contents. In
addition, in a class of 100 or more it is difficult to accommodate
students of slower learning capabilities. It is not possible to

provide individualized assistance required to complete an understanding

1

2
of the concepts and principles in a conventional format of two hours
of lecture and two hours of laboratory per week. It has also been
difficult to provide well-trained instructors with the practical experi-
ence necessary to fulfill students' needs for topical information
in the laboratories. The simultaneous creation of more than five
agricultural colleges in Brazil without prior infrastructure prepara-
tion has caused serious problems in training the "new" agricultural
engineer.

For these reasons, a change from the traditional lecture model
of instruction to one involving the use of audiovisual self-instruction
modules might overcome a number of the instructional problems in teach-
ing of agricultural subjects in developing countries such as Brazil.

While a number of studies comparing traditional and audiovisual
instruction have been done in the United States, with favorable results
for the audiovisual self-instruction method, few, if any, have been
performed in Brazil. Therefore, that research was needed to assess
the effectiveness of audiovisual instruction compared to traditional
instruction in Brazil, specifically addressing the teaching of an
agricultural engineering subject.

In this study an attempt was made to evaluate the audiovisual
self-instruction method in Brazilian agricultural engineering colleges
for teaching agricultural mechanization subjects.

Since a great many variables influence the learning process,
it was essential that a pilot study be performed to-ascertain the
effect of several variables and identify those of greatest importance.

The pilot study would, therefore, address the following issues:

3

(1) Determine the applicability of audiovisual modules
created in the United States as a prototype;
(2) Compare the differences, if any, in learning and
attitudes between urban and rural universities; and
(3) Examine the differences, if any, in learning and
attitudes between small, medium, and large class
size.
Following the pilot study, the main study would be performed
in order to assess the effectiveness of audiovisual instruction com-

pared to traditional instruction in Brazil.

Chapter II
LITERATURE REVIEW

 

The literature review is organized as follows: first, advantages
and limitations of traditional instruction (lecture); second, advan-
tages and limitations of individualized audiovisual self-instruction;
third, the characteristics of successful, well—designed, audiovisual
self-instruction; fourth, previous research comparing audiovisual
with traditional instruction in the United States; and fifth, the

context of Brazilian higher education.

2.1 Traditional Instruction (Lecture Method)

The lecture is an instructional technique, the dominant charac-
teristic of which is an oral presentation by an instructor on a parti-
cular subject. The technique is commonly used to transmit information,
explain ideas and principles, and give assignments. As a technique,
it is a one-way communication channel in which the teacher is a source
of information and the students are relatively passive receivers of
that information. When the lecture technique is augmented by examples,
questions and visual presentations, the broader term "lecture" method

is more appropriate (Davis and Alexander, 1977).

2.11 Advantages of the Lecture Method

 

Abedor (1979) points out the following advantages of the lecture

method:

Effective where knowledge acquisition is
primary goal.

Effective for immediate and delayed recall,
especially for low-ability students.
Efficient in rate of transmission of
information.

Economical with regard to teacher/student

ratio.

Alexander (1977) quoted the following advantages and limitations

of the lecture method:

Advantages

The lecture is a very efficient method for communi-
cating facts, concepts, and principles. It is economi-
cal of staff time, permitting the teacher to cover
large amounts of material.

It permits the teacher to use his/her experience and
knowledge in an organized and systematic presentation
and thus provide information not readily found in
texts or the common experience of students.

It is amenable to recording (audio, video, film) and
transcription.

It can be used with large numbers of students.

It provides opportunities for students to develop
the ability to listen accurately and critically.

It can be stimulating and enhance student's desire
to learn the subject matter.

It requires little or no spacial instructional
equipment or materials.

2.12 Limitations of the Lecture Method

 

1. The lecture method makes it difficult for the
teacher to accommodate student's differences in
background or rate of comprehension.

2. The lecture method places heavy reliance on
student's listening skills, memory and note-
taking ability.

3. It demands sustained student concentration.

4. It provides limited opportunity for active
student participation.

5. It provides little opportunity for judging
audience understanding or reaction accurately.

6. It is inadequate for developing high-level
intellectual skills, i.e., problem-solving.

2.2 Individualized Audiovisual Self-Instruction

 

Individualized instruction refers to a wide variety of instructional
techniques hiwhich students proceed at their own pace to reach an
educational goal. Such techniques are designed to accommodate individual
differences among students in learning styles, motivation, personality,
knowledge, and skills. Individualized instruction techniques differ
in the degree to which students and teachers share the responsibility
for setting the instructional goals, structuring the learning process,
and evaluating the knowledge and skills acquired. The following are
examples of several individualized instruction techniques (Alexander,
1977).

l. Performance-Based Learning Packages
2. Computer-Assisted Instruction

3. Audio-Tutorial Instruction

7

Audio-tutorial instruction is a learning package that uses a
wide variety of media in the teaching-learning process. The instruc-
tional materials may consist of audio and video-tapes, photographic
slides, or motion pictures, in any combination. Students usually
work in individual study carrels, but may be instructed to leave the
carrel to perform a task that applies the knowledge they have learned.

Individualized instructional techniques have been used effectively
in every academic discipline for teaching a wide variety of intellec-
tual skills, from acquiring and applying facts, concepts, and principles
to interpreting information and solving problems (Alexander, 1977).

Since the 1960's there have been highly influential approaches
to individualized instruction at the college level: Postlethwaiter's
Audio-Tutorial Method (1964), Bloom's Mastery Learning (1976), and
Keller's Personalized System of Instruction (PSI, 1968). The most
research at the college level was done with the Keller Plan which
was first used at the University of Brasilia (Brazil) in 1964 and
developed by psychologists Fred Keller, J. Giomaur Sherman, Carolina
Murtucelli, and Rodolfo Sazi. S. N. Postlethwait (1969), Professor
of Biology at Purdue University, began using taped supplementary lectures
in 1961. He gradually added various visual materials for the students
to use. This apparently was the beginning of what is now known as
the "Audiovisual Self-Instruction System."

Audiovisual self-instruction is an ideal method for use in engi-
neering technology courses that require learning a manipulative skill
(Lindenlaub, 1970), because examples can easily be given and the student
can stop the tape while practicing skills. The learner can review

the slide-tape to check if the correct procedure is being followed.

2.21 Advantages of Audiovisual Self-Instruction

 

Advantages of audiovisual self-instruction cited by Alexander

(1977) are:

1.

Individual instruction accommodates individual
differences among students. Students may learn

at their own rate and review materials as frequently
as necessary. It is particularly effective for

slow learners and results in a high rate of retention.

Lessons are planned and designed to achieve predeter-
mined outcomes. Lessons are validated to ensure learning.

Students are challenged and motivated because they

are responsible for and can control their own

learning progress; they actively participate; fre-
quent feedback on progress is provided; and achieve-
ment is evaluated on the basis of an explicit standard
and not in comparison to other students.

Student's and instructor's time are used efficiently.
Content and procedures are standardized and reproducible.

The teacher can continuously monitor the progress
of each student.

Abedor (1979) describes the effectiveness of self-instructional

programs and summarizes as follows:

1.

More effective than traditional instruction with
low-ability students for knowledge acquisition,
concept and principle learning, if designed to
include active practice and feedback.

Efficient use of student and teacher time (cost).

More effective than traditional instruction with
high-ability students (study skills).

S. N. Postlethwait et a1. (1969) presents a summary of the self-

instruction that may be helpful.

1.

The emphasis is on learning by the student,
not on teaching.

The student controls the pace of advancement
through the course.

ll.

12.

13.

9

Progressive students are able to choose their path
of progress.

The student chooses the time for using the
course material.

The student is able to concentrate on the taped
presentation.

The instructor is able to give each student more
individual attention.

Scheduling of the course is usually simplified.
Such a system can usually handle more students in
less space or fewer facilities than conventionally
taught classes.

Make-up labs or review sessions are easily handled.

Students become aware of their responsibility toward
learning.

Senior staff members are able to tutor each student
as needed.

The "packaged" self-instructional courses are easily
used at locations other than the home university.

Audio-tutorial systems of instruction are ideal for
research or learning processes.

Davis et a1. (1974) have explained nine general principles of

learning and motivation that may have influence on the students:

1.

A student is likely to be motivated to learn
things that are meaningful to him.

A student is more likely to learn something new
if he has all the prerequisites.

The student is more likely to acquire new behavior
if he is presented with a model performance to
watch and imitate.

The student is more likely to learn if the presen-
tation is structured so that the instructor's mes-
sages are open to the student's inspection.

A student is more likely to learn if his attention
is attracted by relatively novel presentations.

lO
6. The student is more likely to learn if he
takens an active part in practice geared to
reach an instructional objective.
7. A student is more likely to learn if his
practice is scheduled in short periods distributed
over time.

8. A student is more likely to learn if instruc-
tional prompts are withdrawn gradually.

9. A student is more likely to continue learning
if instructional conditions are made pleasant.

A closer look at these principles of learning and motivation
approaches to the Brazilian agricultural engineering college students
is warranted. The first principle is concerned with the meaningfulness
of the material from the student's point of view. Students will be
more receptive to information if they can relate its use or importance
with regard to their own need throughout the well-stated objectives
and goals.

The second principle supports the needs for incoming students
to have the necessary background skills and knowledge before attempting
to learn new concepts or skills. Pretests can be used to determine
what the student knows when entering a course. .Remedial work is some-
times necessary to ensure that students are adequately prepared before
new instructional material is presented.

Case studies are often used to develop a better understanding
of more advanced kinds of problems and appropriate means of solving
them. Support for following these practices is given by the third
principle. The fourth principle points out that there is no room
for ambiguity in a learning situation.

Novel or unusual methods of presentation can be used and still

not confuse the students. The use of different media often helps

ll

achieve some degree of novelty that is mentioned in the fifth princi-
ple. The sixth principle creates a big difference between self-
instructional method and conventional methods. Students can be re-
quired to actively participate in the learning process by the inclusion
of hands-on exercises during periods of instruction.

Principle seven also creates a big difference between self-
instructional and conventional methods because the self-paced instruc-
tion can be easily used in the first method, given information in
small amounts and the length of the instructional period can be kept
short, if desired.

Gradual withdrawal of prompts (hints) is indicated in the eighth
principle for introducing new concepts or principles in self-instruc-
tional methods. When the course or lesson is being developed into
a self-instructional method it creates many good benefits for learning
and motivation in introduction lab-classes or review sessions. The
ninth principle deals with the learning environment.

These principles of learning and motivation must be kept in mind
in order to see the benefits of transferring and developing a new
method of instruction.

The audio-tutorial method of instruction has gained wide accept-
ance in many academic disciplines since its first application to bio-
logy by Postlethwait (1971) in 1961. By and large, the audio-tutorial
method of teaching has proven to be successful under the right condi-
tions. The original rationale for using audi-tutorial instruction
was that of improving efficiency and/or effectiveness of student learn-
ing. More recently, audio-tutorial instruction has been seen as a

way to reduce instructional costs for large enrollment courses. Since

12

1961, there has been considerable development of audio-tutorial pro-
grams in response to: (l) improving efficiency of student and faculty
time; (2) student satiety with conventional large lecture-laboratory
models of instruction; and (3) differences in student attitudes (Edu-
cational Development Program, 1974).

Audio-tutorial instruction places more responsibility on the
learners and requires greater activity and involvement in the learning
process. Students in an audio-tutorial learning center are noted
for their increased activity and sincerity in studying the materials
while at the carrels or in doing related investigations (Stephen,
1971). The role of the teacher also changes from a "disseminator
of information" to a "guider of learning experiences" (Lambert, 1970).

Some of the learning activities and methods (Postlethwait, 1971)
that audio-tutorial instruction is well-suited to provide are:

(1) learning at the student's own pace; (2) concentration on subject
matter with minimal outside distractions; (3) direct contact with

the material being studied by the use of soils, plants, models, and
other such devices; (4) appropriate sized units of subject matter;

(5) use of instructional media best adapted to the nature of the objec-
tives being studied; (6) use of multi-media such as slides, tapes,

and movies; and (7) integration of learning activities and situations.

An audio-tutorial format can provide individualized learning
experiences that more nearly meet the specific learning needs of each
student than traditional methods. However, problems may be encountered
if some students are not motivated to learn on their own or cannot

adjust rapidly enough to the system (Connolly and Sepe, 1972).

13

2.22 Limitations of Audiovisual Self-Instruction

 

Limitations noted by Alexander and Davis (1977) are:

l. Individualized instruction requires extensive
time to prepare and validate package;

2. It permits little social interaction or summary
integration of material unless specifically
planned for through discussions, debriefings,
or peer-assisted learning sessions.

3. It requires management procedure and data
collection.

Brainard (1975) made the distinction between the Personalized
System of Instruction (PSI, also known as the Keller Plan) and the
Audie-Tutorial(AT) approach. In an audio-tutorial course, the inde-
pendent study sessions frequently do not permit much opportunity for
pursuing individual goals, as students follow the same prescription.
The integrated quiz sessions do seem to provide an avenue for an indi-
vidual's particular interests and competencies to be explored and
developed.

In summary, Brainard says that individualized instruction, at
present, is realized to only a small degree in our contemporary educa-

tional institutions.

2.23 Individualized Instruction vs. Traditional Instruction

Gagne et a1. (1974) in their book Principles of Instructional
.Qesigfl, make the comparison between the traditional lecture method
and an individualized instruction method. Table 24lcompares the differ-
ences as discussed by Gagne and Briggs.

Gagne et al. (1974) added to the previous discussion that the

primary difference between the traditional methods of instruction

14

Table 2-1. Traditional vs. individualized instruction methods.

 

 

Traditional Individual Instruction
Instruction Lecture Alternative means (slide,
tapes, etc.)
Presentation Group Individual basis
Scheduling Set class time Flexible time for viewing
materials and length of
time spent
Scope of Material Limited depth and Depth and amount covered
quality covered can vary with individual
student
Instructor-Student Time per student Instructor can spend
Interaction limited more time per student if
needed

 

and those based on individualized instruction is not how learning occurs
but how the learning environment is set up and controlled. Self-
instruction systems of individualized instruction are designed to

place the learner in surroundings that provide privacy and allow him

to work at his own speed. Instruction materials that are included

let the learner progress toward a particular goal and provide feedback

to him.

15

2.3 The Characteristics of Successful, Well-
Designed Audiovisual Self-Instruction

During the past several decades, research on the teaching-learning
process has identified several characteristics of instruction which,
if present, can improve learning regardless of the media of delivery,
i.e., via television, textbook, slide-tape, or live lecture (Gagne,
1965, 1970, 1974). These nine characteristics of successful, well-
designed audiovisual self-instruction was restated and summarized
in seven characteristics by Learning Evaluation Services at Michigan
State University and published by Abedor (1979) and shown in Table
2-2.

While these seven characteristics are important, all seven may
not occur in every session of a course. However, all of these charac-
teristics should be incorporated at some point in the course. Thus,
these seven characteristics may not occur in any special order. These
characteristics should be viewed as parts of an instructional cycle
which is repeated until the course is finished.

There is much research that supports these seven characteristics
such as: Mager (1966), Abedor (1979), Gagne and Berliner (1974),
Lindenlaub (1974), Diamond (1973), and many others.

Mager (1966) and other researchers support the characteristic
of "the instruction should specify the intended learning outcomes."
They favor communicating of the intended learning outcomes to the
students, and believe that if students know exactly what it is they
are to learn, they will be better able to focus their listening, note-
taking and general studying behavior and consequently improve their

learning.

16

Table 2-2. Summary of characteristics of effective instruction.

 

Characteristic

Techniques

 

Gain and maintain attention

Specify intended learning
outcomes

Orient and motivate learners

Present new information
in organized manner

Require learner to practice
and provide feedback

Provide redundancy

Frequently evaluate learner
achievement

Stimulus variation--voice, visual
aids, rate, etc.

Provocative questions, demonstra-
tion, analogy.

For entire course, units and
individual lessons.

Provide overview and explain pay-
off to learner.

Inductive or deductive organization,
hierarchical, chronological, spatial,
or spiral sequence.

Ask questions or assign problems
of moderate difficulty after each
teaching sequence.

Give feedback as soon as possible
after each practice exercise.

Audiovisual and conceptual.

Exams should measure achievement
of the specified learning outcomes.

Frequent testing and feedback
allows more time for improvement.

 

 

 

17

Related to the characteristic of "the instructor presents new
information in an organized manner", Gage and Berliner (1977) mentioned
that the learning may often be improved: (1) if the information to
be learned is logically organized, and (2) if the underlying organi-
zation is made explicit to the students. Logical organization refers
to the conceptual framework or "road map" which shows the relationship
between a series of ideas. For example, mathematics has an inherent
hierarchical structure, but psychology does not. In general, evidence
indicates that showing students the structure of a module or lecture
as it unfolds provides them with clear signals of transition between
lesson segments and is probably more effective than exposing the under-
lying structure entirely at the beginning or end of the lecture (Abedor,
1979).

Gage and Berliner (1974), in regard to the characteristics of
"the instruction should include practice exercises and feedback",
commented that the human brain has awesome forgetting power and their
research on forgetting has generally found that after meaningful infor-
mation is learned, approximately 50% will be forgotten in one day
and 80% in fourteen days without intervening practice.

Lindenlaub (1974) suggests the reason engineers seem to like
the idea of using self-instruction may be because the primary instruc-
tional mode is still verbal (like lectures) and such a system is fairly
simple to start. Preparation of self-instruction is not radically
different from preparing lectures. Students using the audio-tapes
seem to be at ease listening to them, especially if the instructor

has made the tapes.

18

The relation of visuals and words for developing programmed audio-
visual materials has been studied by Gropper (1966). He found that
while concepts and principles can be acquired on the sole basis of
visual presentation, to rely only on visual lessons is inefficient.

He concluded that words serve an important cueing role and should

be incorporated, for this secondary purpose, into a visual prepara-
tion (Diamond, 1973). Techniques of presentation that allow the stu-
dent to control his own rate of progress are known as self-paced
methods of instruction. Variation on the rate of learning must be
considered as alternative methods of course presentation are developed.

Until recently, most college courses in Brazil were still taught
with a presentation form that is suited more to students who learn
at a faster rate. Interest is growing in developing countries in
methods of presenting course material that allow the learner to more
readily match his rate of progress to his rate of learning.

Johnson et a1. (1970) showed a number of other features that
made self-instruction systems attractive for use in engineering educa-
tion. One of these is the fact that the developer has considerable
freedom to choose the kind of media to be used. Video tape, 35mm
slides, strip film, 8mm movies and printed materials have all been
used successfully. Another feature is that self-instruction courses
are self-contained and can be easily stored or transported to locations
remote from campus. A feature that keeps the self-instructional system
on a human level (as compared to computer-aided instruction, in parti-
cular) is that an instructor can be present to help students if the

need arises.

 

19

Miller (1975) has found that video cassette systems and 8mm films
are excellent audiovisual aids to classroom instruction at the high
school level in reference to small gasoline engines to improve the
instructional process for motor skill development.

Wispe (1951) reported that his lower ability students "enjoyed"

a permissive method but "preferred" the more directive method. Pre-
sumably, preference here indicated a recognition that the directive
method resulted in greater achievement. Patterson and Janicki (1979)
found that students initially preferred an approach in which they
thought they would have to work less hard.

In training seamen to take soundings, Vernon (1946) reported
findings on the role of silent film-strips and sound films in concep-
tual learning. Comparisons of film and filmstrips; filmstrip and
"normal instruction" were made in various classes of above and below
average intelligence and with the best and poorest instructors. Vari-
ables found to be reliable and most influential in prompting learning
were: (1) the filmstrip, (2) the film, (3) a good instructor, and
(4) high intelligence. The significance of this study is that either
the film or the filmstrip not only increased learning of detailed
facts but also extended understanding on the conceptual level (Hoban
and Van Ormer, 1950).

As a further refinement in research comparing visual material
for instruction, Dwyer (1973) designed a study to determine the degree
of effectiveness of three different modes of presentation. College
students were selected as subjects; the content was an instructional

unit on the human heart. The three methods of presentation (television,

20

slides and programmed instruction) used the same script but within
each of the methods the subjects were subdivided into one control

and four treatment groups. Illustrative materials for each treatment
varied in complexity from simple line drawings to photographs of an
actual heart specimen.

Generally, the test results indicated that the three methods
of presenting the content material without additional illustrations,
were equally effective in facilitating student achievement on all
five criterial measures. Results of adding illustrative materials
in each method showed that students viewing simple line illustrations
on television or slides achieved significantly higher scores on the
drawing test than students using programmed instruction.

In treatments using detailed drawings or photographs of a model
of an actual heart specimen, the critical test for identification,
terminology and comprehension showed that the program instruction
method was significantly better than either television or slides.

It was noted that the internal pacing of the programmed instruction
might have been the determining factor in facilitating achievement.
As the illustrations became more complicated, individual students
controlled the time needed to absorb additional information.

A relative effectiveness study by Ortigiensen (1954) compared
filmstrips, sound films and printed materials in: (1) teaching infor-
mation about and (2) changingattitudes toward soil conservation. He
found that film strips were significantly more effective in achieving
cognitive objectives than sound motion pictures, and both were more
effective than printed materials. Filmstrips and sound films were

effective in changing attitudes as were printed materials.

21

In general, findings show that instructional media influence
attitudes and opinions if the content of the media is closely related
to the existing beliefs and social norms of the audience. Messages
designed to effect attitudes are most successful when stimulating
or reinforcing existing beliefs of the learner. Little or no success
has been found if the content is contradictory to the social norms
held. It appears that the more specific the message, the greater
the influence in reinforcing attitudes or effecting the change.

J. J. Gibson (1947) found that aviation cadets learned and remem-
bered more about the system of position firing from a training film
than they did from a classroom lecture with slides or from study of
a well-illustrated manual. An analysis of test items showed that
the film did its more superior teaching in dynamic items dealing with
a sequence of events or with variations of one procedure with another.

Smith (1968, 1969) conducted a series of experiments in.which
one study compared televised with non-televised instruction in an
engineering course at 27 technical colleges in England, where the
British Broadcasting Company television series was used. There were
no significant differences between groups on the attainment test used
to assess the instructional effects of the two treatments. However,
corresponding analysis showed that television broadcast had greater
impact on students who were above average in ability and increased
the general student performance level in mechanics. The investigator
suggested that visual presentation of content might be an advantage

in subject matter requiring understanding of spatial relationships.

22

Baker and Popham (1965) studied the value of embellished visual
presentations based on the suggestion of Lumsdaine and Gladstone (1958)
that the viewer is more receptive to such materials. The embellished
slide set included related, but not realistic, colored cartoons illus-
trating the key verbal content of the accompanying audio tape. The
control slide set consisted of the same verbal material printed on
slides having plain colored backgrounds. Results confirmed two of
the expected differences in affective response: viewers favored the
embellished version of the program on measures of interest and those
of enjoyment. There were no significant differences in other affective
or cognitive measures.

Studies in Ohio have shown that the two-year agriculture students
consider placement training and agricultural courses as the two most
important factors for job placement after graduation (Iverson et al.,
1970). In a survey they conducted, two-year students indicated that
the relevancy of the subject matter to their major, along with grades,
were the prime motivational factors for studying that particular sub-
ject.

Conflicts are found in laboratory studies (Morris and Kimbrell,
1972) which reported a positive correlation between achievement and
enjoyment for a Keller-type mastery approach to an introductory psycho-
logy course. However, closer inspection of their data suggests that
the correlation may be misleading. Higher ability students seemed
to enjoy the mastery method but learned less from it than from the
conventional lecture approach. Lower ability students, on the other
hand, seemed to enjoy the conventional method but learned more from

the mastery approach.

23

Holloway and Robinson (1979) found a negative correlation of
- .21 between achievement and enjoyment of more and less structured
methods of teaching high school students factual information about
a fictitious Indian tribe. The interaction between ability and treat-
ments was non-significant but tended in the same direction as the
Morris and Kimbrell (1972) data. Alderman (1978) has reported a nega-
tive correlation between two outcomes in large scale evaluations of
the use of the TICCIT CAI (Computer Assisted Instruction) Program
for mathematics. Students preferred conventional lectures but learned
more TICCIT.

The negative correlation between achievement and enjoyment seems
to extend to situations where students are allowed to choose between
different instructional methods. Salomon and Kendell (1976) tested
fourth graders' predispositions to perform well in open or traditional
classrooms. They found evidence that students were poor judges of
the setting in which they would achieve the most. Clark (1980) report-
ed that there is considerable evidence in Attitudinal Treatment Instruc-
tion (ATI) studies that students tend to like that instructional method
from which they learn the least. When other things are equal, high
ability students prefer more structured and directive methods, but
learn best from more open and permissive approaches. It seems to
be the low ability student who is most vulnerable to this negative
correlation between learning and liking. Both ability groups seem
to make inaccurate judgments about the efficiency of their efforts.
High ability students appear to believe that more directive instruc-
tional methods will make their learning job easier but those methods

sometimes interfere with their learning by providing strategies which

24

duplicate those they have already learned. Low ability students seem
to conclude that more permissive approaches are more enjoyable, perhaps
because they think that they can achieve as well with them as with

the more directive methods, which require more effect.

Under some conditions novelty will add to the enjoyment of an
instructional method for all ability levels. Finally, Clark recommend-
ed more research to clarify the reasons why students enjoy methods
which do not enhance their achievement.

Dick and Carey (1978) suggested considering two types of revisions
in any instructional materials. The first is changes that need to
be made in the content or substance of the materials to make them
more accurate or more effective as a learning tool. The second type
of change is related to the procedures employed in using the instruc-
tional materials. For more detailed analysis can be provided by dis-
playing the performance of each individual student in the formative
evaluation for each objective. This will be done throughout tabular
pesentation of the data or by displaying data through the use of vari-
ous graphing techniques considering the objectives and performance
on the pretest and posttest exam. The same authors found that the
best way to summarize data from an attitude questionnaire is to indi-
cate on a blank copy of the attitude questionnaire the percent of
students who chose each alternative to the various questions and the
open-ended item. General responses from the students can be sum-

marized then at the end of the questionnaire.

25

2.31 Evaluation

 

Davis et a1. (1974) said that a comprehensive plan of evaluation
will yield information about three aspects of the developer's concerns:
(1) the level of achievement of students entering the learning system,
(2) the level of achievement of students leaving the learning system,
and (3) the level of efficiency and effectiveness of instructional
methods used in the learning system.

Russell (1974) suggested the following guide for a good evaluation
program that will supply the answer to the question :whg learns what

under which conditions and in how much time?" To start to answer

 

these questions it is necessary that the instructor must know where
the student actually started when he began the course. According

to Diamond et al. (1975), few faculty are actually aware of what or
how much the entering students know about their courses. It is desir-
able to give pretests to determine how much the incoming student al-
ready knows about the course content (Bolvin, 1968).

Gagne et a1. (1974) pointed out two types of evaluation: (1) for-
mative evaluation that is concerned with collecting evidence on the
feasibility and effectiveness of the course and usually results in
revisions and improvements; (2) cumulative evaluation is concerned
with the effectiveness of a course after it has been developed, check-
ing if the objectives of the course are being met.

Perhaps the most important characteristic of a useful learning
objective is that it identifies the kind of performance which will
be accepted as evidence that the learner has achieved the objective

(Mager, 1962). In evaluating individualized instruction a statement

26

describing what the learner is like after completing instruction is
needed. Without the learning objective, assessment of the instruc-
tional method cannot occur (Goldschmid and Goldschmid, 1972).
Research on effectiveness made by Blaney and McKie (1969) found
a clear advantage in terms of superior posttest achievement for
students who had been given learning objectives. They also concluded
that learning objectives are more effective than a general introduc-
tion. Comparisons of specific learning objectives versus general
objectives by Jenkins and Deno (1971) yielded no differences between
groups. Dalis (1970), on the other hand, reported superiority in

learning for the group given precisely stated learning objectives.

2.32 Testing

In addition to evaluating performance, Briggs (1970) suggested
that testing is a necessary step in the early stages of tryouts and
revisions of new material. According to the recommendations made
by the Learning and Evaluation Service (1978) at Michigan State Univer-
sity, testing must be included in a systems approach to develop a
self-taught course. This is an important characteristic of a well-
designed module in assessing whether or not the learners achieved
the desired objectives at the end of the instruction. They pointed
out two kinds of tests: (1) the enroute self-tests for each module
objective with the purpose being to enable the learner to assess his/
her progress in a non-threatening way prior to the criterion self-
test. By helping students immediately identify their weak areas,
they will be able to take remedial action and bring themselves up

to criterion performance before it is too late; and (2) the criterion

 

27

test is a mechanism to evaluate if the objective has been satisfactorily
achieved; hence, whether the learner is ready to go on or whether
more instruction is needed. Since the learner is assumed to be working
independently, the criterion test must be self-administered.

Juola (1977) pointed out the properties of different types of
test questions such as: (l) the basic role and function; (2) advan-
tages; (3) disadvantages or limitations; and (4) suggestions for writing
a test item. Olson (1977) noted the check-points for good test items
as follows: relevance, content balance, efficiency, fairness, reli-
ability, difficulty, discrimination and technical soundness.

Dick and Carey (1978) suggested that for revising "instructional
materials" one should:

1. Examine the data with regard to the entry
behavior of the students;

2. Review the pretest and posttest data as
displayed on the instructional analysis
chart;

3. Examine the pretest scores to determine the
extent to which individual students and the
group as a whole, already have acquired the
skills which the instructor teaches;

4. Re-examine the instructional strategy asso-
ciated with various objectives with which
students had difficulty.

Lawson (1974) contended that the evaluation of instructional
materials can be conducted in a formative mode, that is, by describing
and judging the quality of an instructional sequence during its devel-
opment phases. Results obtained from formative evaluation are of
value to those individuals directly involved in the development of

the product, in that they may critically re-examine the proposed

28

instruction materials. He showed one example of determining cost/
effectiveness of instructional products.
Ronzheimer (1973) estimated that it required 1200 to 1300 hours

to develop typical courses using the audio-tutorial method.

2.4 Previous Research Comparing Audiovisual with
Traditional Instruction in the United States

Studies of the effectiveness of individualized instruction for
teaching vocational agriculture in high schools have been conducted
by McCarley (1969) and McVey (1970). The former study was conducted
at four different high schools using an individualized instructional
unit consisting of four lessons and review for grain sampling and
grading. The effect of teaching by this method was found to be signi-
ficanlty better than the lecture-discussion method. Students acquired
more knowledge and skills using a combination of psychomotor and cog-
nitive skills than using cognitive skills alone. Students in the
individualized instructional group were more enthusiastic and tried
harder regardless of their academic rank. The student evaluation
of the individualized instruction unit clustered toward the positive
end of the semantic differential scale.

McVey (1970) used the audio-tutorial units on farm credit, animal
health, commercial fertilizer, and small engines in 12 schools in
Iowa and he found highly significant differences between pretest and
posttest scores using audio-tutorial and control methods.

A video-audio, self-tutorial vegetable: crops course for four-
year degree students was studied by Flocker (1972). Results from

the two-term study showed that students truly enjoyed the experience,

29
learned more from this method than from the lecture method and retained
the knowledge longer.

Green et a1. (1973) reported on a study of an audio-tutorial
system known as Personalized Learning and Narrated Tutorial System
(PLANTS), where the students using the audio-tutorial methods learned
more than students subjected to traditional methods.

In soil science a successful audio-tutorial program has been
reported by Foth (1967). A five-credit introductory course with four
lectures and two-hour lab per week was changed to one lecture, a dis-
cussion period and a three to four-hour audio-tutorial program. Stu-
dents completed a reading assignment, noted objectives and then started
the audio-tutorial unit. Conclusions reached were that Structured
Learning and Teaching Environment (SLATE) could be developed that
produce more learning and that are more personalized.

Cooper (1975) made comparisons between the control group (conven-
tional lecture-laboratory used in 1972 and 1973) and the experimental
group (audio-tutorial mastery learning method used in 1974 and 1975).
He found: (1) student achievement in Soil Science 051 increased as
compared to the lecture-laboratory program, (2) students with success-
ful achievement had more positive attitudes toward the instructional
strategies, (3) student opinion indicated the experimental group
accepted the audio-tutorial mastery learning strategy as useful and
desirable, (4) finally, the audio-tutorial mastery learning program
is appropriate for other courses in the Institute of Agricultural
Technology.

In investigating the effectiveness of five different modes of

audio-narration in combination with motion pictures and still slides,

30

Allen, Cooney and Weintraub (1968) found no significant difference
when considering the visual presentation variables. In terms of atti-
tude toward the presentation model, there was an indication that motion
sound films were perceived more positively than slides.

In general, data on student attitudes toward mode of instruction
are inconsistent and show little relationship between attitude and
measured learning. Preference for specific modes of instruction appears
to vary not only with individuals but also with respect to content,
instructors involved and physical environments available.

McVey (1970) determined the effectiveness of an audio-tutorial
technique in vocational agriculture using six treatment schools and
six control schools which were randomly selected from 48 Iowa high
schools qualifying for participation in the study. While each school
was provided the same reference material and teaching outline for
the 14-day experimental period, the treatment schools were provided
audio-tutorial machines and programs of 20 minutes maximum length
with 59 slides or less in the four subject matter areas of instruction.
Results showed no significant differences between the audio-tutorial
and the control schools in magnitude of change in knowledge for each
of the four class level comparisons. Statistical techniques to adjust
for differences in mean scores resulted in a significant value for
the audio-tutorial technique effectiveness in teaching farm credit.

The audio-tutorial technique was as effective as the control technique
in teaching animal health, commercial fertilizer, and small gasoline
engines. The purpose of the study developed by Rowsey (1974) was

to analyze two methods of instruction used in an animal biology course.

31

One group of students, the experimental group, was taught using an
audio-tutorial program, and another group, the control group, was
taught using the conventional lecture-laboratory method. Pretest

and posttest data were collected from achievement and attitude instru-
ments. An opinion questionnaire and time reports were also analyzed.
The major findings were: (1) students taught using audio-tutorial
instruction demonstrated significantly greater achievement gain but
did not differ significantly in attitude toward course content;

(2) an analysis of the opinion questionnaire revealed a favorable
reaction by the experimental group toward the use of the audio-tutorial
method of instruction; and (3) the experimental group spent a signifi-
cantly greater amount of time in formal study than those students
taught by the conventional approach.

Ott and Macklin (1975) found that students who chose between
conventional and audio-tutorial methods of learning college physics
achieved less than those who were assigned arbitrarily to one method
or the other. Peterson and Janicki (1979) have noted a consistently
negative relationship between pretest preference and posttest measures
of enjoyment with the method of choice for high school and college
students.

Finally, Hetzel (1979) conducted research with agricultural engi-
neering services course students at Michigan State University comparing
an audiovisual self-instruction method with traditional lecture and
found: (1) no significant difference between these methods of instruc-
tion, (2) students indicated that they liked having statements of

behavioral objectives to identify important concepts in course material,

32

(3) past farming experience was not an important factor in the per-
formance of students taking the course in the audiovisual self-instruc-
tional format. Finally, the researcher recommended that other courses
offered by agricultural engineering departments be developed in the)

individual self-instructional format.

2.5 Context of Brazilian Higher Education

 

The development of a higher education system in Brazil is examined

by Silva (1976):
The first stage starts in 1931 with the enactment
of the so-called "statutes of the Brazilian Univer-
sities." It would constitute the most important
attempt to establish a system of universities in
the country. The beginning of the second stage is
marked by the Law of Guidelines and Fundamentals
of 1961. This law intended to reform the entire
educational system as well as to provide the basic
guidelines for its decentralized growth. The third
stage of development begins with the University Reform
of 1968, which attempted to restructure the higher

education system. This reform is still in process
and has been made much more flexible.

Silva's research concluded by saying that the change in Brazilian
higher education has moved from a rigid structure to a more flexible
one as a result of the University Reform. As a consequence of these
changes more recent developments in overall structure of the higher
education system is characterized by a decrease in the number of uni-
versities, from 64 in 1971 to 57 in 1974, while the number of auto-
nomous institutions increased from 555 in 1971 to 773 in 1974. This
process is shown in Table 2-3. -

In his essay, Rios (1971) did a great deal of empirical research

on the charactieristics of the Brazilian students and the nature of

33

Table 2-3. Undergraduate enrollment: 1974.

 

Distribution of Students Number of Students % of Students

 

Total 937,593 100%
Basic Cycle 243,818 26.10
Professional Cycle 693,775 73.90
Enrolled in Universities 409,185 43.64
Enrolled in Autonomous

Establishments 528’408 56°36
In Federal Institutions 205,573
In State Institutions 90,618 36.00
In Municipal Institutions 44,837
In Private Institutions 596,565 64.00
Biological Sciences and

Health Professions 116’626 12°45
Exact and Technological

Sciences 190,736 20.36
Agricultural Sciences 19,667 2.00
Social Sciences 477,721 51.00
Letters and Arts 89,473 9.56
Other 42,863 4.63

 

Note: Figures reflect enrollment in the beginning of the academic year.

Source: Anuario Estatistico do Brasil, 1976, Vol. 36.

 

the Brazilian

1.

34

university. He found that:

Brazil finds itself today in a stage of develop-
ment similar to that of the United States before
1880.

Students appear to have a more accurate notion of
the job market than do those responsible for the
direction of the educational system.

Student's decisions are influenced by critical
opinion, news openings, newspaper editorials, and
conversation with professors and fellow students.

Twenty-seven point four percent (27.4%) of the
students depend exclusively on work for their
maintenance; 35.9% depend exclusively on the
family for their expenses, and 26.2% are partially
dependent upon family.

In summary, 68.8% are maintained partially or totally by the

family. In student expenses, the significance of fellowships is slight;

only 0.8% of the student sample indicated this.

MSU-BRAZI
at agricultura

engineering an

L Project Report Number 13 (1976) contains a close look
1 engineering, specifically curricula for agricultural

d includes observations and recommendations such as:

The effectiveness of teaching and the efficiency of
utilizing the limited teaching personnel should be
continually improved through:

a. Reducing the number of in-class student
contact hours required per week for each
discipline and course as a whole;

b. By requiring more self-study on the part
of students;

c. By making textbooks available to students;

d. By developing meaningful laboratory exercises

that require each student to complete measure-
ments, analyze data, and formulate conclusions.

Chapter III
A PILOT STUDY TO COMPARE A PRELIMINARY MODULE OF
AUDIOVISUAL INSTRUCTION WITH TRADITIONAL INSTRUCTION

3.1 Purpose of the Study

In considering the use of audiovisual instruction in Brazil,
there were a number of questions that needed answers. Therefore,
a brief pilot study conducted in Brazil was considered the best
method to obtain answers to these questions. This information could
then be used as the basis for further study comparing traditional
with audiovisual instruction in Brazil.

The pilot study addressed the following five areas:

1. To determine if there would be significant
differences in amounts of learning between
audiovisual self-instruction and the traditional
lecture method in an agricultural college in
Brazil.

2. To identify those components in the preliminary
version of the audiovisual self-instructional
module which would need modification to improve
its effectiveness with Brazilian students.

3. To test for differences that might exist between

students at rural and urban universities.

35

36

4. To determine if class size would have an influence
on learning from audiovisual and traditional
instruction.

5. To assess the attitudes of Brazilian students

toward the audiovisual instruction.

3.2 Design of the Study

 

In this section, the preliminary audiovisual module and lecture
treatments are described, as well as the papulation and sample selec-
tion, the test and evaluation instruments, the testable hypotheses,

and the design to analyze the data.

3.21 ngulation and Sample

 

Fourteen Brazilian universities with agricultural colleges formed
the population for this study. Three agricultural colleges, randomly
selected, served as the sample from the population of fourteen.

The first agricultural college selected was the University of
Federal Rio de Janeiro (RJ), located in a rural area, 47 kilometers
from the city of Rio de Janeiro. The total number of students in
the Agricultural College was 731 (males and females). A total of
131 students were randomly selected from 193 students registered in
agricultural machinery.

The second university selected was the Federal University of
Pelotas located in South Brazil in the state of Rio Grande do Sul.
This state is characterized mainly as having high agricultural produc—

tion of the following crops: rice, wheat, soybeans, corn and fruits.

37

The university is located 25 kilometers from the city of Pelotas.
The total number of students in the agricultural college was
635 of which 112 were registered in the course of Agricultural Machin-
ery. There were 60 students selected at random from a group of 112.
The third university selected was the Federal University de Porto
Alegre located in the state of Rio Grande do Sul, 10 kilometers from
the city of Porto Alegre. The number of students registered in the
Agricultural Machinery course was 107 from which 36 were selected.
The instructor of this Agricultural Machinery course also taught the
same course at Pelotas University, necessitating his traveling more
than 120 km every weekend to teach the students on Saturdays. The
classroom used for the audiovisual treatment was the same as that
used for the traditional lecture. Only the University of Rie de Janeiro
had prepared a facility for audiovisual presentation. At the two
other universities with only classroom facilities, the rooms were
modified as required for the audiovisual presentations, e.g., with
dark curtains, projectors and rearrangement of the desks.

The population under investigation was comprised of agricultural
students in their second year (third semester) of undergraduate work.
The total sample for this study consisted of 227 second-year
undergraduate Brazilian students. Their distribution is shown in
Table 3-1. As previously stated, the criterion of selection was

random.

38

Table 3-1. Number of subjects per unit for the treatment Versus
university interaction effect.

 

 

 

University
Rio de Janeiro Pelotas Porto Alegre
Method U U U TOTAL
1 2 3
Traditional 67 32 19 118
Audiovisual 64 28 17 109

 

3.22 The Evaluation Instrument

 

A pre and posttest were developed to assess student learning from
audiovisual and lecture treatments. In developing the pre and post-
tests the recommendations of Davis et a1. (1975) were used. For example,
in comparing the effectiveness of the two alternative treatments,
it was necessary to measure the number of objectives achieved by stu-
dents at the end of instruction. These test results served as the
basis for comparing the effectiveness of the treatments in teaching
specific objectives.

The instrument developed consisted of 15 multiple choice questions
(Appendix A) to evaluate the six objectives.

The questions were grouped by objective with importance factors
and weighting from low (1) to high (5) level of content (Table 3-2).

Objective 1: Without the aid of references, students should

 

be able to identify (orally or in writing) the main parts

and the available attachments for the moldboard plow.

Table 3-2.

39

 

 

Distribution of test items across the objectives and
weighting.
Weighting
Objective Item Number Factor

1 9-10-11 1

2 6-8 2

3 1-2-3 3

4 l3 5

5 14-15 4

6 14-5-12 4

 

Objective 2: Without the aid of references, the student
should be able to describe (orally or in writing)
functions of the main parts of the moldboard plow.

Objective 3: Without the aid of references, the student
should be able to describe (orally or in writing)
the mechanical action of the bottoms of the mold-

board plow and its attachments.

 

Objective 4: Without the aid of references, the student
should be able to identify the forces acting in the
center of load and its elements to further determine
the center of load.

Objective 5: Without the aid of references, the student

 

should be able to choose (orally or in writing) the
correct moldboard plow considering the land conditions

and the tractor.

40

Objective 6: Without the aid of references, the student

 

should be able to describe the adjustment process of
the moldboard plow and its attachments correctly.
The instrument was used as a pretest to determine the equivalency of
the groups of students, which is basic to comparing the effectiveness
of the two instructional treatments. A great deal of research has
demonstrated that the most critical factor in determining student
achievement in an instructional unit is how much he knows about the
material to be covered upon entering the unit. Consequently, it was
essential to control this factor in comparing the two methods of in-
struction.
To evaluate the questions derived to test achievement of the
six objectives, consideration was given to the properties of a good
testing instrument. These include validity, reliability, objectivity
and discriminability or differentiality (Davis et al., 1974).
Validity - Definition: a test is valid when it requires
the learner to perform the same behavior under the
same conditions specified in the learning objectives.

Reliability - Definition: a reliable test provides a

 

consistent measure of a learner's ability to demonstrate
achievement of an objective.

Objectivity - Definition: a test has objectivity if two

 

or more competent observers can independently judge
whether or not a learner's test performance meets the

criteria stated in the learning objective.

41

Differentiality - Definition: a test has satisfactory

 

differentiality if it includes tasks that only

learners who have achieved the objectives can perform.

The strategy used to enhance validity was to write the test ques-
tions immediately after writing an objective. This insured correspon-
dence between the behavior and conditions stated in the learning objec-
tives and the criterion measure for that objective. Since it is diffi-
cult to write a definitive test item for an ambiguous objective,
this procedure helps the researcher recognize an objective that is
not written in behavioral terms, or an invalid test item.

Test reliability was enhanced by reducing extraneous factors
such as: unclear instructions, ambiguous test items, test conditions
that were different from those stated in the objective, the use of
jargon, the introduction of a type of test that the students had not
experienced, and finally, student anxiety.

Test objectivity was examined by having a colleague competent
in the area take the test without referring to the scoring key. By
determining that the test designer and his colleage agreed upon the

answers, the test objectivity was established.

3.3 Attitudinal Measure

 

In addition to the achievement test, an attitudinal measure was
administered to 38 students randomly selected from the audiovisual
classes, to measure their perceptions regarding several aspects of
the preliminary audiovisual module. The purpose of this evaluation

was to gather data to further improve the audiovisual instruction.

42

The instrument and the technique used for this evaluation was developed
by Abedor (1971).

The attitudinal evaluation instrument (Appendix 8) included 16
Likert-type rating scale items, seeking to measure several factors
of the module which were analyzed descriptively. One item (#17) was
stated as an open-ended question to be interpreted by the author,
encouraging students to express opinions and perceptions not encoun-

tered in the Likert items. (See Table 3-3.)

Table 3-3. Factors and item numbers of the attitudinal measure.

 

 

Factor Item Number
1. Prerequisites l
2. Objectives 2
3. Organization 4
4. Evaluation 11
5. Type of resource and frequency 12
6. Rate of presentation 5
7. Redundancy 6
8. Lack of information 7
9. Interest and attention 3
10. Clarity of instruction 8
11. Examples 9
12. Vocabulary level 10
13. Degree of revision needed 15
14. Attitude toward subject matter 16
15. Certainty of learning 13
16. Amount of learning 14

 

43

3.31 Scoring and Display

 

The attitude survey was scored by the author. A numerical value
from one to five points was assigned to each response; five points
represented dissatisfaction and one point represented the "ideal"
response. An appropriate arithmetic correction was made before scoring
so that all items would conform to the same scale.

The interpretation of the "open-ended" item (#17) used a scoring
system of percentages.. If 30% of the responses expressed similar

themes, the implications were considered by the author.

3.4 Hypotheses

 

The results of both treatment groups - (1) traditional method
and (2) audiovisual method - were analyzed to determine whether the
following three null hypotheses could be rejected when checked against
the six objectives.

The alpha level for this study was set at P = 0.05.

The three hypotheses are stated as follows:

Hypothesis I - There is no interaction between
universities and methods of instruc-
tion as measured by student per-
formance.

Hypothesis II - There is no difference between the
two methods of instruction as mea-
sured by student performance.

Hypothesis III - There is no difference between the
methods of instruction as classified
by class size and measured by student
performance.

Each of the three hypotheses were tested against the six objectives.

44

In Figure 3-1 the hypotheses and individual test objectives are
identified by hypothesis (Roman numeral) followed by objective (Arabic
number), e.g., III-5 indicates Hypothesis III tested against Objective
5.

3.5 Design of the Statistical Analysis

 

The three hypotheses in this study were organized by objectives
into six sets. For a given set, the first two hypotheses were analyzed
by two-way analysis of variance. The two independent variables were:
(1) treatment (which had two levels - traditional and audiovisual
method); and (2) universities (which had three levels: University
Federal of Rio de Janeiro, Porto Alegre and Pelotas).

Given this 2 x 3 design, there were three possible hypotheses
that could be tested. However, only the interaction hypothesis (#1)
and the treatment main effect hypothesis (#2) were interpreted. The
main effect of the university is discussed only when it was significant.
For any significant effect a Scheffé contrast was used to compute
the range of the effects.

For the third hypothesis of each of the six sets, a one-way analy-
sis of variance was employed.

The second design consisted of an independent variable which
was developed by a combination of treatment by class size. This inde-
pendent variable had four levels, distributed in the following manner:
for traditional method, large (G1) and small (G2) class size; for
audiovisual method, average (G3) and small (G4) class size. Table 3-4

displays this distribution.

45

OBJECTIVES

 

zopa vcmonupos on»
mo ucosumanuo on» onwgummv oh

zopn ugmoaupos uumcgou as» mmoogu op

veep on» mo gmucmu mg» cw
mcwuum neocoe may xwwucmuw oh

zopa vgmonupos msa we meoauoa on» we
m=o_pum quwcmsume msu mnpcommu oh

zopa cement—cs on» co mecca
ewes ecu co mcopuocam onwcumwu o»

zopa ucmonu—os esp mo mucwsnomuum
use magma ewes asp zw_a:muw o»

HYPOTHESES

 

I-3 I-4 I-5 I-6

I-2

I-1

universities and teaching

No interaction between
method (I)

II-2 II-3 II-4 II-5 II-6

II-l

(II)

No effects of class size

methods of instruction
on methods of instruc-

No difference between

III-4 III-5 III-6

III-2 III-3

III-1

(III)

tion

 

Identification of the hypotheses across

six objectives.

Figure 3-1.

46

Table 3-4. Distribution of class size by group and treatment.

 

 

Method Group Class Size
Traditional G1 (large)* 62 (small)*
Audiovisual G3 (average)* G4 (small)

 

*Large = 30 students, average = 20 students, small = 10 students.

It should be noted that it would have been preferable to have two
independent variables, teaching method and class size. However, there
are not enough subjects to make the level of class size fully crossed
with teaching method. This was resolved by combining the class groups
that could indirectly give information about the teaching method as
it was influenced by class size.

If the main effect of the four groups was significant, a Scheffé
post-hoc procedure was used to test significance. The effect of class
size within audiovisual instruction was of particular interest.

The first contrast examined was the difference between the audio-
visual and the traditional methods for those students in the small
class (G4 vs. GZ)'

The second contrast examined was the difference between students
in the small class size and the average class size of the audiovisual
method (G4 vs. G3). These two statistical tests (i.e., two-way and

one-way ANOVA) were repeated for the six objectives.

47

3.6 Methodology

 

All treatments were administered in August and September, 1978.
One week was devoted to testing at each university. The approach
used for each treatment was to use the same instructor and the same
topic, "The Use of Moldboard Flows in Tillage Operations." The evalua-
tion instrument was used to elicit feedback regarding needed improve-
ments in the audiovisual module.

The traditional lectures were taught by the author in all classes
to minimize differences between classes.

The usual resource was the blackboard and chalk. The lecture
startedvfitiian introductory explanation regarding the purpose of the
research and overview of the steps, and their time allotment. There
were:

15 minutes for the pretest

50 minutes for the lecture

25 minutes for the posttest

80 minutes total for the traditional lecture per class

The audiovisual class was introduced with a similar explanation
regarding the objectives of the research and the time distribution
for the steps. There were:

15 minutes for the pretest

20 minutes for the audiovisual presentation through
the slides without any interruption

25 minutes for the posttest

60 minutes total for the audiovisual instruction per
class

48

Additional time was required for the audiovisual instruction
after the posttest:

5 minutes of break for randomly selected students
to answer survey questionnaire

10 minutes for additional information and to relieve
students anxiety and facilitate their open and
frank response

15 minutes to answer the questionnaire survey.

The test questions were the same for the pre and posttest exams
in both treatments of instruction.

The resources used for the audiovisual instruction were:

1 slide projector with remote control

1 screen

1 tape recorder

l tape with the class narration in Portuguese

1 10 watt speaker

1 set of 36 slides used for teaching the AET 443
Machinery and Tractor Systems course in the
Agricultural Engineering Department at Michigan
State University. An audio tape translation
of the original English tape was prepared by
the author in Portuguese. (This subject matter
represented content similar to a course in
Agricultural Machinery in Brazil.)

The main constraint observed by the author in using the audio-
visual module was the necessity of viewing the module without inter-
ruption, normally not a constraint of self-instructional modules.
However, this procedure was used to accommodate the stated class sche-
dule for the course in the universities.

Another important variation created by the author was the adoption

of a group audiovisual presentation instead of an individual

49

presentation. This was done because of the economic situation of
Brazilian universities, which would preclude individual viewing because

of cost.

3.7 Results of the Analysis of the Pilot Study

 

The results of the statistical analysis are presented in Figures
3-2 through 3-7. The means for each objective of the six groups are
plotted. Next, the results of the analysis of variance are presented.
For those tests that were significant, post-hoc analyses are shown.
Finally, the results of the attitudinal measurement are presented.

For Objective One (Figure 3-2) the means of the traditional group
are larger than those of the audiovisual group in universities U1
and U2. This difference was not noted for U3.

For Objectives Two and Four (Figures 3-3 and 3-5), the means
of the traditional groups are larger than those of the audiovisual
groups in the three universities. However, the difference between
those groups for Objective Two is larger for U3.

For Objective Three (Figure 3-4) the means are approximately
equal for all universities for both methods.

For Objective Five (Figure 3-6), the means of the audiovisual
group appeared to be larger than those for the traditional group for
U1 and U2, while in U3 the traditional group mean is larger than the
audiovisual group mean.

Finally, for Objective Six, the means of the audiovisual group
appeared to be larger than those of the traditional group for U],

while universities U2 and U3 are approximately the same.

50

.ANNN u zv
HH mwmmspoasz .oze aswauahao

co muumwnam an oucmsgoecwa cam: .m-m ogzmpd
n mmwummcw>wca
Li 0 a

 

mgmm~< oucom m:
mmaopma N
ocwocma mu owm F

II II
2:) D

 

w

- Md
. v.6

.fivo

 

alqissod siuiod unmixew) aaoas ueaw

(91

.ANNN u zv HH memagaoasz .mco a>_puawao

 

     

co muomnnzm x5 oucmELoecma cam: .mum mczmwd
mo. Pmem>F=
mm .uuo . a Fe
0.0
u FoamP>owu=<
. I .. s .2052: so
» no
I
, to ad
I \
x.
z .\
z \
z .\
(x
5.0

 

(gl = alqissod siuiod unmixew) aaoos ueaw

51

.ANNN u zv

HH mwmmsuoa»: .gaom w>puumnao

co mpumnnzm an mucmsgomcma cum:

mmwupmcm>wca

a: mu pull

.m-m menace

 

mcmmp< ougoa
mmuopma
ocwmcmw mu ova

any

 

(gl = alqgssod siugod unmixew) aaoos ueew

.ANNN u zv HH memagaoa»: .amage a>ea
-umnno co mpumnnam an mucmscowgmq cum: .eum mczmwd

 

 

 

mow“ mgm>wcz
31 r. 5

L moo

u Fozmw>oyua<

lllll u chowuwumgh
.oAu
.3
z.mgu

 

alqtssod siutod mnwlxew) aaoos ueaw

(51

52

.ANNN “ zv
HH memagpoa»: .xwm a>wuoaflno

co muownnsm ma mucmsgomcma cum: .num mesmwg

mmwuemgm>wca
no «a 5

 

memmF< opgoa
mmuopmm
ocwwcma mu omm

v:
<3
aaoos ueaw

ixew)

nvmo

lOd mnw

alqissod siu,

(Sl

 

 

.ANNN u zv HH m_ma;aoas= .a>_a

mmwuwmcm>vcs

n: N:

 

u Fmamm>omuz<
In lulu $8532..

m>wpuonno co mpuonnsm xn mucmscowcoa com: .mum wczmwm

F:

170 o

 

ixew) aaoas ueaw

lOd wnw

alqissod s:u_

(51

53

Table 3-5. Results of testing Hypothesis I on Objective 1 (university
versus treatment).

 

 

 

ANOVA Table Objective 1 Hypothesis I
Source of Variation df MS F-Ratio P less than
University x treatment 2 .204 2.680 .070

 

The F ratio for the interaction between university and treatment
was 2.68 with 2 and 221 degrees of freedom. The F test had a prob-
ability of less than .0708 which is greater than .05 resulting in
failure to reject the null hypothesis. The interaction between in-
structional methods and universities was, therefore, considered negli-

gible.

Table 3-6. Results of testing Hypothesis II on Objective 1 (traditional
versus audiovisual).

 

 

 

ANOVA Table Objective 2 Hypothesis 11
Source of Variation df MS F-Ratio P less than
Treatment effect 1 2.1102 27.7001 .OOOl*

 

*Significant at .05 level.

The degrees of freedom for the error term is 221. From the table
it may be seen that the treatment main effect had an F-ratio of 27.001,
with l and 221 degrees of freedom, and the F test was significant
at the .0001 level. Since the probability of a type I error (a) was
set at the .05 level, the null hypothesis of the treatment main effect

54

on Objective 1 was rejected. This provides evidence that there is
a statistically significant difference between traditional and audio-
visual instruction on Objective 1, Hypothesis II.

To further examine the magnitude of the difference between the
traditional and audiovisual groups, the Scheffé post-hoc procedure

was used to find the range of the difference.

Table 3- 7. Mean scores for traditional and audiovisual groups for
all universities.

 

 

Method X U1 X U2 X U3 Average
Traditional .60 .69 .51 .61
Audiovisual .36 .48 .50 .41

 

Table 3- 7 displays data which support the statement that the tradi-
tional method is better than the audiovisual method on Objective 1.
The weighted means for traditional and audiovisual are 0.61 and 0.41,
respectively. The Scheffé contrast for the difference between the
traditional and audiovisual methods, with .05 level of significance,
ranges from 0.12 to 0.27. Therefore, the traditional method is con-
sistently better than audiovisual regardless of the university. The
minimum difference between the traditional and audiovisual methods

of instruction is 0.12; the maximum difference is 0.27.

55

Table 3-8. Results of testing Hypothesis III on Objective 1 (treat-
ment versus class size).

 

 

 

ANOVA Table Objective 1 Hypothesis III
Source of Variation df MS F-Ratio P less than
Treatment versus

class size , 3 1.1643 15.9138 .0000*
Error 223 0.0732

Total 226

 

*Significant at .05 level.

Table 3-E3 displays an F-ratio of the treatment versus class size effect
of 15.9138, which 3 and 223 degrees of freedom. The F test is signifi-
cant at the .00 level. Since the probability of a type I error (a)

was set at the .05 level, the null hypothesis regarding a treatment
versus class size difference on Objective 1 was rejected. This provides
evidence that a significant difference exists between groups of varying

class size on Objective 1.

Table 3-‘9. Mean of variance of class size groups.

 

GROUP CLASS SIZE

 

Method G1 (Large) G2 (Small) G3 (Average) G4 (Small)
Traditional .6263 .5088
Audiovisual .3805 .7333

 

From Table 3-9 two interesting contrasts were chosen:

56

Contrast 1: A difference between the audiovisual and
traditional treatments for only those students
in small classes (G4 vs. GZ)'

Contrast 2: A difference between the average class size

and small class size of audiovisual (G4 vs. G3).

Table 3-10. Scheffé contrasts for class size and type of instruction.

 

 

Contrast Mean Range of the 95% Scheffé Contrast
G4 VS. G2* .2245 - .07 to .5173
G4 VS. 63* .3528 .104 to .6015

 

*G - small traditional; G3 - average audiovisual; and G4 - small
aOdiovisual.

For Objective 1, the 95% Scheffé contrast between small audio-
visual (G4) versus small traditional classes (62) ranges from -.O7
to .5173. Since the range includes the zero value, the difference
between G4 and G2 was not significant. However, the 95% Scheffé con-
trast between the small audiovisual (G4) and the average audiovisual
group (G3) ranges from .104 to .6015 and does not include zero. There-
fore, the difference between G4 and G3 is significant. Thus, stu-
dents who received audiovisual instruction in small classes performed
better on Objective 1 than students who received audiovisual instruc-
tion in an average class size. The minimum difference between G4

and G3 on Objective 1 is .104 and the maximum difference is .6015.

57

The average difference is .35 (or 35%). The difference between G4

and G3 is meaningfully significantfor further research.

Table 3-11. Results of testing Hypothesis I on Objective 2 (univer-
sity versus treatment).

 

 

 

ANOVA Table Objective 2 Hypothesis I
Source of Variation df MS F-Ratio P less than
University x treatment 2 .1894 1.4819 .2295

 

The degrees of freedom for the error term are 221. The F ratio for
the interaction between university and treatment was 1.4819 with 2
and 221 degrees of freedom. The alpha level was less than .2295,
which is greater than .05. Thus, Hypothesis I was not rejected. There-
fore, the difference between the traditional and audiovisual methods

within each university was essentially the same for Objective 1.

Table 3-12. Results of testing Hypothesis II on Objective 2 (tradi-
tional versus audiovisual).

 

 

 

ANOVA Table Objective 2 Hypothesis 11
Source of Variation df MS F-Ratio P less than
Treatment effect 1 2.1102 27.7001 .0002*

 

*Significant at .05 level.

58

The degrees of freedom for the error term are 221. From Table
3-12, it may be seen that the treatment main effect has an F-ratio
of 27.7001, with l and 221 degrees of freedom, and the F test was
significant at the .0002 level. Since a probability of a type I error
(a) was set at the .05 level, Hypothesis II on Objective 2 was rejected.
Thus, the treatment main effect was significant. There is a statisti-
cally significant difference between these two methods on Objective 2.

To further analyze the magnitude of the difference between the
traditional and audiovisual methods, the Scheffé post-hoc procedure
was used to find the range of the difference. As can be seen from
Table 3-13, the traditional method is better than the audiovisual

method for Objective 2.

Table 3-13. Mean scores for traditional and audiovisual groups for
all universities.

 

 

Method X U1 X U2 X U3 Average
Traditional .66 .67 .61 0.64
Audiovisual .41 .55 .56 0.47

 

Table 3-13 shows that the traditional method has a higher mean
than the audiovisual method for Objective 2. The weighted means for
the traditional and audiovisual methods are 0.65 and 0.47, respectively.
The Scheffé contrast for the difference between traditional and audio-
visual methods with .05 level of significance ranges from 0.08 to

0.27. Therefore, the traditional method is consistently better than

59

the audiovisual one. The minimum difference between both methods

is 0.08 and the maximum difference is 0.27.

Table 3-14. Results of testing Hypothesis III on Objective 2 (treat-
ment versus class size).

 

 

 

ANOVA Table Objective 2 Hypothesis 111
Source of Variation df MS F-Ratio P less than
Treatment versus

class size 3 .7825 6.1284 .0005*
Error 223 .1277
Total 226

 

*Significant at .05 level.

Table 3-14 shows that the F-ratio of the treatment versus class
size main effect is 6.1284 with 3 and 223 degrees of freedom. The
F test is significant at .0005; thus, the effect of class size is
significant at the .05 level. This provides evidence that signifi-
cant differences exist between treatment and class size for Objective

2.

Table 3-15. Mean scores for class size and type of instruction.

 

Means of Group Size
Method G1 G2 G3

Traditional .6612 .6053
Audiovisual .4495 .6500

 

60

To further examine the differences between groups of the two

independent samples, a Scheffé post-hoc procedure was used.

Table 3-16. Scheffé contrasts for class size and type of instruction.

 

 

Contrast Mean Range of the 95% Scheffé contrast
G4 VS. 62 .0447 - .3419 to .4315
G4 VS. 63 .2005 - .1280 to .5290

 

For Objective 2, the 95% Scheffé contrast between small audiovisual.
(G4) versus small traditional (G2) ranges from - .3419 to .4315. Since
the range includes the zero value, the difference between G4 and G2
were not significant. Also, the 95% Scheffé contrast between small
audiovisual (G4) and average audiovisual group (G3) ranges from -.1280
to .5290. Therefore, as this range includes 0, the differences between
G4 and 63 may not be interpreted as significant. Though the main
effect is significant, the two contrasts of interest are not. The
difference between the two class sizes in the audiovisual method,
which is about .2 (20%), is not large enough to be statistically or
educationally significant.

The results of testing Objectives, 3, 4, 5 and 6 are presented
in Table 3-17 which summarizes the main statistical findings. The
information is presented in this way because the statistical results
were not significant for any of the hypotheses stated for these

objectives.

61

Table 3417.Results of testing Objectives 3, 4, 5 and 6 (university
versus treatment, traditional versus audiovisual method,
treatment versus class size).

 

Anova Table

 

 

 

 

 

Objective Hypothesis df MS F-Ratio p less than*
I Source of varia- .01191 .1921 .8254
tion - univer—
3 sity vs. treat-
ment
II Treatment effect .0000 .0000 .9954
Treatment vs.
III class size .0828 .3564 .2570
I University vs. .0725 .3780 .6851
treatment
4 II Treatment effect .6098 .6098 .0759
III Treatmevt VS- .2316 .2475 .2934
class Size
I University vs. .0826 .7838 .4780
treatment
5 II Treatment effect .2007 .9053 .1689
111 Treatment VS- .0880 .8367 .4750
class Size
1 University vs. .0719 .2004 .3031
treatment
6 11 Treatment effect .0740 .2354 .2676
III Treatment VS- .0939 .5559 .2010
class Size
*Significant at .05 level

62

From Table 3-17 for Hypotheses I, II and III belonging to Objectives
3 to 6, the F-ratios were of greater magnitude than the stated value
of type I (a) set at .05, the last row of Table 3-17. Therefore,
those hypotheses were not rejected. This provides evidence that there
is not a statistically significant difference in:
- the interaction between universities and treatments
- the treatment main effect (audiovisual versus traditional)

- the groups of class size and treatments.

3.8 Results of Attitudinal Measures of the Pilot Module

 

Thirty—eight students from audiovisual classes responded to the
post instruction attitude survey which was scored by the author. A
numerical value from one to five points was assigned to each response,
one representing the ideal response and five representing dissatis-
faction. Those items that had a reversed scale were changed to direct
scoring to correspond with the others.

The items were examined by their means and standard deviation
values. The statistical results of the mean and standard deviation
are shown in Table 3-18, and also the mean is plotted in Figure 3-8.
The students' comments are shown in Appendix C and interpreted in
Table 3-18.

The following range of means was established in order to discuss
the results:

Items rated as GOOD range from 1.00 to 2.700.

Items rated as UNCERTAIN range from 2.701 to 3.300.

Items rated as NEEDING REVISION range from 3.301 to 5.000.

63

Table 3-18. Results of attitudinal measure of the pilot study.

 

 

X Standard

Factor Mean Deviation
l. Prerequisites 1 3.947 1.314
2. Objectives 2 2.799 1.228
3. Organization 2.706 1.068
4. Evaluation 11 2.447 0.891
5. Type of response and frequency 12 3.103 1.539
6. Rate of presentation 5 3.650 1.133
7. Redundancy 6 2.000 0.771
8. Lack of information 7 3.605 1.220
9. Interest and attention 3 1.711 0.927
10. Clarity of instruction 8 1.658 0.847
11. Examples 9 2.342 1.146
12. Vocabulary level 10 2.947 1.229
13. Degree of revision needed 15 3.768 1.101
14. Attitude towards subject matter 16 2.000 0.870
15. Certainty of learning 13 3.447 1.132
16. Amount of learning 14 2.750 1.287

 

64

or mp @—

.A>v=um po—wav meameme._mcwu=uwuum mg“ we magma .wfm weaned

emassz xn msmufi mewmccowpmmzo
me» up pp 0. m m n o m e m u —

 

lllllllllI'll-111111111111lll.l.ll.l.laL

0')
uteiaaaun

poos

uotstnau paaN

 

(8£=N) mail auteuuotisano paemol ap01l11v Butiuasaadea asuodsau ueaw

65

From Table 3-18 and Figure 3-8 established for the range, the

means were grouped as follows:

Good items 3-6-8-9-11-16
Uncertain items 2-4-10-12-14
Need revision items 1-5-7-13-15

The items located in the "good" range are related to interest
and attention, redundancy, clarity of instruction, examples,
evaluation, and attitude toward subject matter. These items
were considered as not needing any improvement.

The standard deviation for items 3, 6, 8, 11, and 16 was a
low valueTOess than 1.0) indicating less student discrepancy in
answering these items and greater validity in results. Another
interesting finding of the "good" items is that the students showed
greater acceptance of the audiovisual module as a resource of instruc-
tion (items 3 and 16).

The items that fell into the "uncertain" range were related
to objectives, organization, vocabulary level, type of response
and frequency, and amount of learning. These items were interpreted
mainly by considering the standard deviation which was greater than
1.0. These items were identified as needing further revision.

Finally, the items that were located in the range of "need
revision" were those associated with prerequisites, rate of presen-
tation, lack of information, certainty of learning and degree of
revision needed. These items are important and their results combined
with the treatment results determined the extent of improvement
needed in the audiovisual pilot module in order to become better

suited to Brazilian students.

66

From Table 3-18 the prerequisite factor had a mean of 3.947.
This indicated that the students did not have enough preparation
for the lesson. Two factors may explain this finding: first, the
audiovisual instruction was totally unfamiliar '03 all the students,
and second, there was lack of entry behavior of the Brazilian students
regarding the topic.

The information factor (item 5) had a mean of 3.650. This
indicated that the Brazilian students felt that there was an overload
of information in the module. The results of testing item seven
reinforced this data.

Item 13 was asked as follows:

"At the end of the lesson, I was still uncertain about

a lot of things and had to guess on many of the post-

test questions."
The mean for this item (13) was 3.447 indicating that the Brazilian
students did not learn well from the audiovisual instruction and
many items in the posttest questionnaire were "guessed at".

The results from item 15 were important as they revealed the
expressed need by the Brazilian students for modification of the
audiovisual pilot module before using it with other students.

Table 3-18 shows themean value of 3.768. This relatively high value,
along with other associated results, must be considered when evaluating

the audiovisual pilot module for instruction in Brazilian universities.

3.81 Results of the Open-Ended Questions

Item 17 is as follows:

Please write below any comments, suggestions, or changes
which you believe will improve this lesson. Thank you.

67

Thirty students answered this question. Their comments are

shown in Appendix C and the results are in Table 3-19.

Table 3-19, Results of open-ended item #17 grouped according to the
percentage of frequency.

 

 

Factor Percentage
1. Acceptance of the audiovisual method. 95%

2. The rate of presentation was too fast. 80

3. Overload of information. 80

4. Require slide with legends in Portuguese 40

5. Revision of the audio tape (sound, volume) 35

6. Congratulations to the author for the

initiative. 45

 

3.9 Conclusions of the Pilot Study

As a result of the pilot study, the following conclusions were
reached.
1. Changes were needed in the audiovisual treatment.

Since previous research had indicated the superiority of
audiovisual instruction over lectures, it was surprising to find either
no significant difference or that traditional instruction was superior.
This finding was attributed to the following. First, the audiovisual
module used in the pilot study was designed for students in the United

States and had not been adopted for Brazilian students, e.g., it did

68

not have appropriate Portuguese legends on the slides). Second, the
module had not been designed in accordance with the best practice

in audiovisual module design. For example, there was an excessive
amount of narration for each slide.

2. The number of’objectives needed to be reduced.

Another conclusion reached in this study from the student response
was that there were too many objectives being sought in both traditional
and audiovisual treatments; therefore, changes were needed to reduce
the number of objectives. Since the evaluation instructions were
related to objectives, the need arose to modify the assessment instru-
ments to be in accord with the smaller number of objectives.

3. A need for simplification of the statistical design was
demonstrated.

Since class size and type of university made no difference in
the pilot study, it would be desirable to simplify the statistical
design so that a single university and a single class size would be
the unit of analysis in the main study.

4. The introduction of'audiovisual instruction had great
acceptance by Brazilian students.

Therefore, a study of the economic feasibility is needed to provide

complete information for the introduction of the new method.

Chapter IV
DEVELOPMENT OF THE REVISED AUDIOVISUAL INSTRUCTION MODULE
AND ITS COMPARISON T0 TRADITIONAL INSTRUCTION

The following steps were taken to modify the audiovisual module
(based upon results and conclusions of the pilot study):
I. Revision of the audiovisual module to better suit
Brazilian students.
II. Revision of the objectives and tests.
III. Revision of the statistical design.
IV. Application of the attitudinal measurement.
V. Determination of the cost effectiveness of the
audiovisual module.

4.1 Revision of the Self-Instructional
Audiovisual Module for Brazilian Students

 

In revising the module for Brazilian students, the following
points were considered:
A) Inherent problems of Brazilian universities.
B) The characteristics of the ideal teaching-learning
situations.
C) A workable design process for developing the audiovisual
module.
These are discussed below.

69

70

4.11 Inherent Problems of Brazilian Universities

The teaching-learning situation in Brazilian universities follows
a pattern of high numbers of student classroom hours (26-30 per week).
This requires an excessive amount of faculty classroom time and appears
to be a carryover from a time when textbooks were not available.
Lectures often continue hour after hour, thus exceeding the desired
amount of time for effective learning. Frequently, such scheduling
is necessitated because professors work only part-time and/or have
long travel distances.

References and textbooks in most of the universities are very
modest. There are few books in Portuguese on basic agricultural engi-
neering areas. This is a serious handicap to the students and needs
both local and national attention.

The amount of time available for homework and analytical problems
is not great due to the time spent in the classroom. Course outlines
for the advanced agricultural engineering disciplines indicate a modest
amount of analytical work is planned due to the limitations explained
above.

The limited number of faculty members with agricultural engineer-
ing advanced degrees presently available and anticipated in the near
future is another characteristic of Agricultural Engineering Colleges
in Brazil.

Students enrolled in the course come from widely varying back-
grounds and lifestyles. Both rural and urban areas are represented

in the classroom.

'71
4.12 Characteristics of the Ideal TeachingeLearning Situation
Research during the last several decades on the teaching-learning
process has identified several characteristics which, if present,
clearly improve learning (Abedor, 1979). A well-designed instruc-
tional process should:

1. Specify and evaluate predetermined learning outcomes.

2. Gain and maintain the learner's attention.

3. Orient and motivate the learner.

4. Present new information in an organized manner.

5. Require the learner to make responses and provide
feedback on these responses.

6. Provide self-pacing and/or redundancy.

7. Be piloted on representative learners and revised
as required.

To the degree these characteristics are incorporated in the

module, learning will be improved.

4.13 A Workable Design Process for Developing Audiovisual Modules

To design the self-instructional module, a sequence of eight
tasks was chosen (based upon a Learning and Evaluation Service [M.S.U.]
Handbook, 1980). The performance of these tasks by the author was
considered essential in developing an improved self-instructional
module for Brazilian students. Each task in the process is explained
briefly below.

Design Task 1: Determine rationale (need for and feasibility)

of self-instructional modules.
Design Task 2: Determine specific self-instructional module

topics and state what skills, knowledge or attitudes

 

72

(objectives) students are expected to learn.

Design Task 3: Construct a self-test to assess whether students

 

have achieved each intended learning outcome (objective).

Design Task 4: Outline and sequence the substantive content

 

needed to achieve each intended learning outcome (objective).

Desiganask 5: Determine the format and treatment of the module.

 

Design Task 6: Prepare a story board or manuscript outline.

 

Design Task 7: Produce the audiovisual and printed materials.

 

Design Task 8: Try out and revise module.

 

These eight design tasks were done according to the instructions

stated in worksheets l to 5 (Appendix 0). Two versions - English

and Portuguese, were developed (Appendix E). The instructional format

used was as follows:

INTRODUCTION

1. Module Identification (title, author and course)

2. Administrative Instructions (how to use the module
and materials needed)

3. Overview (describes briefly the topics in the module,
how they relate to each other and how the module
rates to other modules)

4. Motivation (why the information in this module is
important to the student)

5. Objectives (specific learning outcomes of the module)

6. Prerequisites (what students are expected to know

prior to starting the module)

INSTRUCTIONAL SEQUENCE (repeated for each major topic or objective)

1.

Transition (relates the topic of the instructional
sequence to previously presented information)

Presentation of the New Information (explanation and
examples)

73

3. Self-Check Exercises and Feedback (to enable students
to assess for themselves their understanding of the
new information just presented)

CONCLUSION

1. Summary and Review of Major Ideas

2. Criterion Self-Test

3; What To 00 Next If:

Criterion test is passed.
Criterion test is failed.

The main changes made in the revised audiovisual module were:

1) To reduce the number of the objectives as is explained on
the following page.

2) To increase the number of slides from 35 to 54 to improve
the presentation of the subject and to avoid the overuse of the same
slide and loss of attention.

3) To make the slides with a Portuguese legend. This is an
innovative technique that was perfected after several attempts. Labels
were printed with a labeler and placed on the picture (book or magazine)
for copying. The advantage of this technique was redundancy (verbal
information as well as pictorial) that increased the learning effec-
tiveness.

4) To improve the taped narration of the script by using native
speakers of Portuguese.

5) To prepare worksheets and a color printed copy of the module
slides which would facilitate immediate feedback and evaluation by
the students, without going back to the slides.

The color printed copy of the module slides (Appendix E) was

one of the primary approaches considered by the study to facilitate

74

introduction of the module in countries where the following problems
and conditions exist:
Problems:

Lack of textbooks

Lack of economic resources

The heterogeneous background of students

The high number of students per class

Conditions:

 

Free time during the evenings

The desirability of immediate revisions of the content

The individualized revision of the modules through
printed modules could be decreased

The disadvantage of a group audiovisual instructional
mode.

6) To introduce the formative evaluation process stated by Abedor
(1979). Figure 4~1 shows the process that was used in order to get
information for further improvement of the audiovisual module.

The entire process includes: (a) selection and orientation of
3—6 volunteer students who are representative of the target population;
(b) group use of the prototype lesson materials by these volunteers;
(c) administration and scoring of criterion test and attitudinal mea-
sures to provide a basis for problem identification; (d) identifica-
tion of major problems to be discussed with students; and (e) leading
a group debriefing and problem solving interaction. The objectives
of the group debriefing are twofold: (l) to clearly identify major
deficiencies or instructional problems in the prototype; and (2) enable

students to contribute suggestions regarding elimination of these

75

.mmmuoea cowumape>m m>wpeEcod

 

 

 

 

‘

 

mcowammzo
umccmucmqo
on» m~>ch<

Ill

 

 

msmpnoea

sceeeeee
ucm mmezmmmz

meoom

 

mmezmmmz

pecwu=u_pp<
wee mcwceeog

Leencewee<

.F-e reamed

 

 

 

mpzuoz
mnxnopoem
mm: mucmvapm

 

azoeu ummeah
seem mucmcaum
mum pompmm

 

 

 

 

 

76

problems. In the present study, the debriefing step was replaced by

an open-ended question.

4.2 Revision of Module Objective and Test

The module objectives were revised as follows:

First, the number of objectives were reduced to three to decrease
the overload experienced by the Brazilian students in the pilot study.

Second, these objectives (three) were stated following the instruc-
tions specified in worksheet 2 (Appendix 0).

Third, the objectives' content was limited to the cognitive domain
which involves concepts, facts, and principles. The level of learning
was limited to knowledge, comprehension and application. Table 4-1

shows the type and level related to the test items.

Table 4-1. Distribution of the items according to module content
of the objectives.

 

 

Objective Type Level of Learning Test Items
Objective 1 Concept Fact Knowledge 3-4-5-7-8
. . Knowledge and 11-13
Objective 2 Concept Fact Comprehension ]0_]2_14
Objective 3 Principles Application 15

 

The objectives and test questions were revised by three instruc-
tors, with the same area of expertise. Two were from the Agricultural
Engineering Department at Michigan State University and one was from

the Brazilian Agricultural College.

77

The three revised instructional objectives were:

OBJECTIVE 1: Without the aid of references, the student will be
able to identify (orally or in writing) the main parts and
attachments and to describe the functions of the moldboard
plow according to the information provided during instruction
(slide and cassette or lecture) with an accuracy of 80%.

OBJECTIVE 2: Without the aid of references, the student will be
able to describe (orally or in writing) the mechanical action
of the moldboard plow, according to the information provided
during the instruction (slide and cassette or lecture) with
an accuracy of 80%.

OBJECTIVE 3: Without the aid of references, the students will be

 

able to compute, locate, and record the center of load of the

moldboard plow, according to the instruction provided to him

in the introductory class (slide and cassette or lecture) and
complimented by lab class using a flow chart.

The audiovisual module was to be used as the primary instruc-
tional resource such that the module provided 111 the instructional
experiences for Objectives 1 and 2. Second, it was also used as
"preparation" for a lab class which would teach material required

for achievement of Objective 3.

4.21 Revision of the Evaluation Instrument Tests

 

Several revisions of the instrument used in the pilot study were
made: First, the questions were related to objectives (see Table

4-2) according to the length of the subject and instructional

78

resources; second, five levels of questions were used in the instrument
(rather than solely multiple choice) which minimized the likelihood
of guessing and in addition to increase the differentiability of the

test instrument (Olson, 1972).

Table 4-2. Distribution of the items according to the objectives.

 

 

Objective Item Number Weighting
Objective 1 1-2-3-4-5-6-7-8-9 1
Objective 2 10-11-12-13-14 1
Objective 3 15 1

 

Table 4-3. Distribution of the items according to type of question.

 

 

Type of Question Item Number
Multiple choice 9-11-14
Matching 4-8-6
Short answer 2-5-12
Fill in blank space 3-7-13
Label 1-10-15

 

Students responded to the instrument twice: before the introduc-
tion of the treatment (as a pretest) and after the treatment (as a
posttest). The pretest was used to determine the pre-experimental
equivalence of the treatment and control groups which was basic to

comparing the effectiveness of the two treatments.

79

In order to evaluate the questions derived from the three objec-
tives, the same procedure was used as described in the pilot study

(see page 40).

4.3 Revision of the Statistical Design

The statistical design was totally revised, taking into account
the results of the pilot study.

1.. The university independent variable was reduced to one level
(Federal Rural Rio de Janeiro) for the main study, because the univer-
sity factor did not interact with the treatments. In addition, the
facilities and personnel within this university were equipped for
this type of study.

2. The independent variable of class size was reduced to one
level, average class size (20 students), for both treatments (audio-
visual and traditional method). This decision was made for research
purposes only. To approach the realistic economic situation of the
Brazilian university (and other developing countries) - where the
number of students are more than 100 per class - additional sets of
audiovisual equipment would be required.

To analyze the three hypotheses (see page 82), a one-way analysis
of variance was used. The independent variable had two levels: audio-
visual and traditional method.

The design had three (3) dependent variables which were stated
as objectives of the revised module and analyzed separately, see

Figure 4-2.

80

Class
.2 .2

1
Audiovisual 20 20 20
Traditional 20 20 20

Figure 4-2 . Number of students per class for the
instructional treatment.

4.4 Application of the Attitudinal Measure

 

The post instruction attitude survey was developed by the author
specifically to measure students' perceptions regarding several aspects
of the audiovisual module they had just finished (Appendix B). Speci-
fically, this instrument was a 17 item Likert-type rating scale seeking
to measure four general factors (Table 4-4). Twenty students selected
randomly from the audiovisual classes responded to the questionnaire,
according to formative evaluation procedures.

Item 17 was stated in an open-ended form to encourage students
to express opinions and perceptions not previously accounted for in

the Likert items.

5.5 Determination of the Cost Effectiveness
of the Audiovisual Module

 

Before the introduction of audiovisual instruction can be seri-
ously considered in Brazilian universities, it is necessary to have
information for estimating the costs of the proposed instruction.

The procedure for calculating the cost of the audiovisual product

include the following economic criteria stated by Lawson (1974):

81

Table 4-4 . Groups, factors and item numbers of the attitudinal

measure.

 

Factor Item Number

 

1)

2)

3)

4)

Audiovisual module strengths and weaknesses resulting from
learning task factors.

a. Prerequisites 1
b. Objectives 2
c. Organization 4
d. Evaluation 11
e. Type of response and frequency 12

Audiovisual module strengths and weaknesses resulting from
communication message design factors.

a. Role of presentation 5
b. Redundancy 6
c. Lack of information 7
d. Interest and attention 3
e. Clarity of instruction 8
f. Examples 9
g. Vocabulary level 10

Audiovisual module strengths and weaknesses resulting from
management technical factors.

a. Degree of revision needed 15

Perceived learning and attitudes resulting from the lesson.

a. Attitude towards subject matter 16
b. Certainty of learning 13
c. Amount of learning 14

 

82

.—J
O

Authoring expense

2. Pilot learners

3. Content adviser

4. Materials

5. Layout/design

6. Typing

7. Reproduction

8. Product manager

9. Hourly development expense of instruction
10. Learner development expense per hourly cost

of instruction

4.6 Hypotheses

 

The results for effects of treatment groups (1) traditional method,
and (2) audiovisual method were analyzed to determine whether the
following null hypotheses could be rejected. The control limit for
the probability of a type one error was set at p e .05.

Ho]: There is no difference between the two methods of

instruction as measured by the student performance
on Objective 1.

H02: There is no difference between the two methods of
instruction as measured by the student performance
on Objective 2.

H03: There is no difference between the two methods of
instruction as measured by the student performance
on enabling Objective 3.

H04: There will be no difference between student attitudes
towards the pilot audiovisual module and student atti-
tudes towards the revised audiovisual module.

In addition to those four hypotheses, the cost-effectiveness

of audiovisual instruction was determined.

83

4.7 Design of the Main Study

 

Three distinct research objectives were sought in this study:
1. Experimental comparisons of student achievement
from the "New Module" audiovisual self-instruction
with the traditional method.
2. By means of an attitudinal measure, determination
of improvement still required by the "New Module."
3. Determination of the cost effectiveness of
audiovisual instruction.
Since the “New Module" was itself a prototype, a description
of the problems and successes resulting from its use was essential

for further modification and refinement of the module.

4.71 Population and Sample

 

The revised audiovisual treatment was used with students from
the University Federal Rural Rio de Janeiro (RJ) Brazil. The decision
to use only one university was made based upon data that showed there
were no important differences between students at the three univer-
sities involved in the pilot study. The population under investigation
was agricultural college students and with the same prerequisites.
From a total of 206 students, 120 were selected randomly (males and
females) from those registered in agricultural machinery courses.

The students were identified by their instructor's class lists
and were randomly sent to the lecture or audiovisual treatment. The
classroom was the same used in the pilot study. The number of students

in each group was 20.

84

4.8 Methodology

 

The module used in the study was to be used in the ongoing course
at the University Federal Rural de Rio de Janeiro, second semester,
1979. The module entitled "The Use of the Moldboard Plow" was developed
for use in the undergraduate service course in Farm Machinery. The
course enrollment was more than 150 students per semester, second
year students, who were heterogeneous in their major fields, motivation,
and background.

The instructional method regularly used in the course consisted
of two lectures and one laboratory per week. With the introduction
of the audiovisual self-instruction, one lecture would be dropped

and replaced with the audiovisual module.

4.81 Procedure

All experimental group treatments involved students' use of the
revised prototype audiovisual materials which had been reviewed by
peers for content accuracy. The experimental treatment module con-
sisted of pictorial information on 35 mm slides and student work-
sheets, audio-information on a tape recording, printed reproduction
of the module, pretest and posttest and post-instructional attitude
survey.

The students were assigned to the audiovisual class and the
traditional classin groups of 20 in keeping with the results found
in the pilot study. The group presentation mode was adopted instead
of individual presentation in order to approach the real economic

situations of Brazilian universities. In the group mode, the

85

instructor controlled a single slide projector and tape recorder with-
out stopping or repeating.

The audiovisual class was started with an introductory explana-
tion regarding the purpose of the research and overview of the steps,
and their time allotment. These were:

10 minutes of introductory explanation
15 minutes of pretest

25 minutes for the audiovisual presentation through
the slides without any interruptions

30 minutes for the posttest

80 minutes total for audiovisual instruction for class

5 minutes break for the randomly selected students
to answer the survey questionnaire

10 minutes for additional information and to relieve
student anxiety to facilitate open and frank
response

20 minutes for answering the questionnaire survey

The traditional instruction was handled by two instructors: the
chairman of the Agricultural Engineering Program and the regular
instructor.

The traditional class was started with a similar introductory
explanation regarding the objectives of the research and overview
of the steps, and their time allotment. These were:

10 minutes of introductory explanation

15 minutes of pretest

50 minutes for the lecture

30 minutes for the posttest

105 minutes total for the traditional lecture per class

86

The procedure and equipment of the traditional and audiovisual
class was the same as was used in the pilot study.

The main constraint observed in addition to those noted in the
pilot study was that the main study experimental treatments were admin-
istered by the Brazilian instructors. The instructions and materials
for performing the study were discussed with the chairman when he

was in the U.S.A. and complimented by written instructions.

Chapter V
RESULTS AND DISCUSSION OF THE STATISTICAL ANALYSES

 

The results of the comparison between traditional and audiovisual
instruction methods when checked against Objectives 1, 2, and 3 were
analyzed to determine whether the null hypotheses presented in Chap-
ter IV could be rejected when the alpha level was set at .05.

The first three hypotheses were tested by a one-way univariate
analysis of variance. The presentation of the results of the analysis '
start with descriptive statistics shown in Table 5-1. This is followed
by the analysis of variance results for each of the objectives.
Hypothesis 4 was tested by comparison of the means of the pilot and

main study.

Table 5-1. Means and standard deviations of the three objectives
of both traditional and audiovisual instructional methods.

 

 

Traditional Audiovisual
SD X SD
Objective 1 g .3722 .1595 .4815 .1412
Objective 2 .2533 .1978 .3767 .2012
Objective 3 .1500 .3601 .2333 .4265

 

The table shows the means and standard deviations on the three objec-

tives and also the means are plotted in Figure 5-1.

87

 

88

 

 

05%
E?
N
,9 O4“
:2
U)
In
C
D.
U)
4.!
C
'8 030
Q
E
3
.E
x
'0
5
0211-
Q)
L.
O
U
(n . .
c —- ---= Traditional V
16
0T 02 0‘3
Objective
Figure 5-1. Mean performance by subjects on

Objectives 1, 2 and 3. (N = 1201*

*Note the lines connectingthe data points in all figures are for
illustrative purposes only and are not intended to show trends.

89

The means of the three objectives for the audiovisual group were
consistently higher than the means of the traditional group (Table 5-1
and Figure 5-1). However, the standard deviation of Objective 3 (to
compute, locate, and record the center of load of the moldboard plow)
was the largest. This means that there was more dispersion among
students in both groups of instruction on Objective 3.

The results of testing Hypothesis 1 are shown in Table 5-2.

Table 5-2. Results of testing Hypothesis I on Objective 1 (tradi-
tional versus audiovisual).

 

 

Source of Variation df MS F-Ratio P less than‘
Traditional versus

audiovisual I '3531 15-7753 .0001*
Error 118 .0227
Total 119

 

*Significant at .05 level. The degrees of freedom for the error term
are 118.

From Table 5-2 the F-ratio is 15.7753, and with 1 and 118 degress
of freedom the F test was significant at .0001. Since the probability
of type I error was set at the .05 level, the null hypothesis of the
effect between audiovisual and traditional methods on Objective 1 was
rejected. Therefore, there was a statistically significant difference
beween audiovisual and traditional methods of Objective 1.

To further examine the range of the magnitude of the difference
between traditional and audiovisual groups, the Scheffé post-hoc pro-

cedure was used. The means for traditional and audiovisual on

90

Objective 1 are: .3722 and .4815, respectively. The 95% of confi-
dence Scheffé contrast for the difference between traditional and
audiovisual groups ranged from 0.06 to 0.16. Thus, the audiovisual
method is consistently better than the traditional method on Objective
1; the minimum difference between traditional and audiovisual is 0.06
while the maximum difference is 0.16. On the average, the difference

between audiovisual and traditional methods is 0.11.

Table 5-3. Results of testing Hypothesis II on Objective 2 (tradi-
tional versus audiovisual).

 

Source of Variation df MS F-Ratio P less than

 

Traditional versus

audiovisual I :2513 5-5530 .0117*
Error 118 .0398
Total 119

 

*Significant at .05 level. The degrees of freedom for the error term
are 118.

Table 5-3 shows that the F-ratio of the group effect is 6.5630 and
with 1 and 118 degrees of freedom the F test is significant at .0117.
Since the probability of type I error was set at the .05 level, this
is evidence that there was a sitatistically significant difference
between the audiovisual and traditional method on Objective 2, and
the null hypothesis: "the effect between groups" on Objective 2 was
rejected.

To further examine the magnitude of the difference between the

audiovisual and traditional groups, a Scheffé post-hoc procedure was

91

used to examine the range of difference. The means for traditional
and audiovisual were .2533 and .3767, respectively. The Scheffé con-
trast for the difference ranges from 0.05 to 0.19. Thus, the audio-
visual method is consistently better than the traditional with regard
to Objective 2. The minimum difference between methods is 0.05, while
the maximum difference is 0.19. On the average the difference between

the audiovisual group and the traditional group is 0.12.

Table 5-4. Results of testing Hypothesis III on Objective 3 (tradi-
tional versus audiovisual).

 

 

Source of Variation df MS F-Ratio P less than.
Traditional versus

audiovisual l .2383 1.3373 .2499
Error 118 .1558
Total 119

 

*Significant at .05 level. The degrees of freedom for the error term
are 118.

From Table 5-4, it may be seen that the effect between methods had
an F ratio of 1.3373, with 1 and 118 degrees of freedom, and the F
test was not significant at .2499. Since the probability of a type
I error was set at the .05 level, the null hypothesis of the effect

between methods on Objective 3 was not rejected.

92

5.1 Discussion of Findings Relative to Posttest Achievement

These data clearly show marked improvement in student achievement
on posttest l for Objectives 1 and 2 using audiovisual instruction.
These results were, of course, precisely the reason for the revision
efforts on the module used in the pilot study.

This degree of improvement between traditional and audiovisual
instruction may be partially attributed to consideration of the seven
characteristics of effective instruction recommened by the Learning
and Evaluation Services Handbook (1979), Michigan State University,
as well as to consideration of the cultural differences of the Brazi-
lian students.

The results of the main study are in accord with results of pre-
vious research. The improvement in student performance in the audio-
visual treatment observed on Objectives 1 and 2 was gratifying and
expected since the data now were in accord with previous research.

A statistically significant difference in student learning was
found only on Objectives 1 and 2, with Objective 3 showing no signi-
ficant difference between audiovisual and traditional instruction.
Upon closer inspection, the researcher found that achievement of Objec-
tive 3 was being measured only by means of one test item out of 15,
and the objective was stated as an enabling objective (the terminal
objective will be measured after the completion of the lab-class).
Since one test item was regarded as an insufficient test of this objec-

tive, the result of no significant difference was to be expected.

93

5.2 Results of the Attitudinal Measures

The questionnaire and procedure used in the main study to assess
attitudes were the same as those used in the pilot study. The differ-
ence was that the items of the questionnaire were grouped in four
factors in order to analyze the strengths and weaknesses of the audio-
visual treatment. Table 5-5 shows the means and standard deviations.
Figure 5-2 shows the graph of the means of the item number and the
range stated.

The results are recorded in such a way that the lower the value
of the mean, the more desirable are the results of the item. Con-
versely, the higher the value the more undesirable are the results.

In Figure 5-2 a range of acceptability is shown.

5.21 Discussion of the Attitude Survey

A discussion of results of the attitude survey follows throughout
the four factors that were associated with specific survey items.
Those factors are:

l. Audiovisual treatment strengths and weaknesses
associated with learning or task factors.

2. Audiovisual treatment strengths and weaknesses
associated with communication/message design
factors.

3. Audiovisual treatment strengths and weaknesses
associated with management/technical factors.

4. Perceived learning and attitudes associated with
the lesson.

The results of most of the items associated with the "learning
or task" factor displayed means of less than 2.700 (Table 5-5) and

they were located in the "good" range section (Figure 5-2). Those

Table 5-5.

94

deviations (main study).

Results of attitudinal measure, means and standard

 

Audiovisual treatment 1 - strengths and weaknesses associated with
"learning or task" factors.

Factor

a. Prerequisites

b. Objectives

c. Organization

d. Evaluation

e. Type of resource

and frequency

Item Number

 

1
2
4
11
12

X

I429.

4.100
2.150
2.650
2.700
2.650

Standard
Deviation

0.968
1.182
1.348
1.174
1.226

 

Audiovisual treatment 2 - strengths and weaknesses associated with
"communication message design" factors.

Factor

a. Rate of presentation
b. Redundancy

c. Lack of information

d. Clarity of instruction
e. Clarity of instruction
f. Examples

9. Vocabulary level

Item Number

 

5

\meNO

10

X

M_ea_i]_
3.200
2.150
3.400
2.250
2.350
3.00

3.250

Standard.
Deviation

1.609
0.988
1.188
1.118
1.348
1.522
1.251

 

Audiovisual treatment 3 - strengths and weaknesses associated with

"management/technical" factors.

 

X Standard
Factor Item Number Mean Deviation
a. Degree of revision needed 15 3.300 1.469

 

Audiovisual treatment 4 - "perceived learning" and "attitudes asso-
ciated with the lesson" factors.

 

X Standard
Factor Item Number Mean Deviation
a. Attitude towards subject
matter 16 1.750 0.786
b. Certainty of learning 13 3.300 1.380

c. Amount of learning 14 .2.550 1.317

 

95

.Axu:um cweEv meammws chwuapwpae mgu we mapsmmc mmcmm .Ntm mesmmu

consaz xn msmuH meweccowpmmao

ehwrIIIIMhIIIthIIIImIIIIImm we or. m. Timiiiiihiiliimiiiiim e multifari. p
)lfl

 

 

 

-"'||II"II"'I'I'II' '''''''''''''''''' 5L,
DJ
M
NO.

'| ' "" ""'| | H- ' ". "|l' "'ln
U
m
”J
AI.-
D.
lo

-'II"|' "'| '''''' "" ""' """"" "Ju
N
a
w.
v
“G
a
A
lo
S
La
0
U

 

(OZ=N) waii auteuuotisano paemoi apnitiiv Butiuasaadaa asuodsaa ueaw

96

items did not need improvement and the factor associated with the
learning factor was considered satisfactory for the revised module.
The exception was item one which had a high mean value which was with-
in the need revision range. This indicated that the student did not
have sufficient entry skills to take the class and none of the stu-
dents had any prior experience with an audiovisual course.
The results associated with the design or communication of audio-

visual factors were distributed in the following way:

a) Good range: Redundancy

Interest/attention
Clarity of instruction

Therefore, these items were considered satisfactory and did not need
revision.

b) Uncertainty range: Rate of presentation

Examples
Vocabulary levels

These three items had mean values between 2.701 and 3.300 (Table 5-5)
and standard deviation values of more than 1.100. This indicated
that students' feelings were not homogeneous. The author recommends
further revision of only items that appeared to be associated with
the comments of item 17 (open-ended question).

c) Need revision range: Lack of information
This item had 3.400 mean value and 1.188 standard deviation. The
mean results were not too far from the uncertainty range and the stan-
dard deviation indicates that the students' feelings were heterogen-
eous. Therefore, this item required more information in order to

assess need for revision. The researcher then asked for an open-

ended response to this item.

97

The general concern about the design factor of the audiovisual
module was considered satisfactory and was not in need of revision.

The results associated with the technical/management factor were
related to item 15 - degree of revision needed. The mean value was
3.000 (uncertainty range) and the standard deviation 1.469 (Table 5-5).
The standard deviation value was considered high. That indicates
a great discrepancy among students in their feelings toward this factor.
Therefore, this factor was considered satisfactory.

Finally, the results associated with "perceived learning" and
"attitudes toward the lesson" were related to items 13, 14 and 16,
and were considered satisfactory.

The most homogeneous feeling expressed by the students in this
attitudinal measure was related to "attitude toward subject matter,"
(item 16), indicating that the students liked the audiovisual instruc-
tion and the low value of the standard deviation displayed this homo-
geneity of feeling.

In general the results of the comparison of the attitudinal measure
of the pilot study (Table 3-18 and Figure 3-8) with the revised module
(Table 5-5 and Figure 5-2) indicated better response to the revised
module and satisfaction with the instruction, with minor revisions

needed. Therefore, Hypothesis 4 was rejected.

5.22 Results of the Comments on the Open-ended Question

Item 17 (Appendix F) was stated the following way: PLEASE WRITE
BELOW ANY COMMENTS, SUGGESTIONS, OR CHANGES WHICH YOU BELIEVE WILL
IMPROVE THIS LESSON. THANK YOU.

98

The number of students who answered item 17 were eleven (11).
Most stated that they needed more time for learning (Appendix F).
This reaction may have been a result of their not being able to stop
the instruction at any point. This problem will be addressed through
use of repetition of and printed reproduction of the module (Appen-
dix E).

The other point commented upon by almost all the students was
the great acceptance of the audiovisual instruction displayed by the
students' comments in the open-ended item (17):

- One of the best methods.
- Excellent system of instruction.

- We need more audiovisual classes.

5.3 Results of Determining Cost Effectiveness
of Audiovisual Instruction

 

 

The procedure developed by Lowson (1974) was used for calculating
the cost effectiveness of the audiovisual instruction method in com-
parison with a traditional mode of instruction. See Table 5-6. The
cost data of the materials was requested and received from audio-
visual suppliers, and the professional salary and other information
from the Brazilian universities.

Table 5-7 shows development cost of traditional instruction.
Comparison of Costs: hourly cost of instruction for audiovisual =
$2.75/student; for traditional = $3.17/student. Difference in the
first year is $0.42 per student. That means that there is a $0.42

savings per student in audiovisual instruction. That will become

99

Table 5-6.

Development cost for audiovisual instruction.

 

Authoring Expense
Author - 20 hours 0 $6.25/hour
Progarmmer - 10 hours 0 $6.25
Narrator - 2 hours 0 $10.00
Pilot learners (free)
Content Advisor - 5 hours 0 $6.25/hour
Materials - 3 tape recorders @ $45.00
3 slide projectors 0 $169.00
3 rolls color slides (36/role) 0 $4.06
Processing of l role 0 $5.25
Diazo process 0 $.30 x 20 slides
Cassette 0 $3.67
Layout/Design - 8 hours 0 $6.25
Typing - 2 hours @ $8.00
Reproduction of 3 sets of 53 slides 0 $25.90

Manager's Expense - planning, organizing, monitoring
and controlling; 5 days 0 $10,00/day

SUBTOTAL
Other (5% of the subtotal)
TOTAL EXPENSE T0 PRODUCE MODULE

 

(Average hours to
complete instruction)

Hourly Development Expense
of Instruction $1156.62/2)

Learner Development Expense/

Hourly Cost of Instruction ($578.32/210)

(210 = number of learns using product in first year)

$125.00

62
20

31.
135.

507.
12.

50.
16.
77.

50.

1,101
55

$1,156.

578.

$2

.50
.OO

00
.55
.09
63

32

.75

 

100

more of a difference after the second year, created by the possibility
of an increase in the amount of audiovisual equipment needed and

diminishing the number of students per group of class.

Table 5-7. Development cost of traditional instruction.

 

Learners: Number = 210
Number of classrooms
Number per classroom

4
52

Instructor: Number = 2
Salary at $1000 each = $2,000

Instructor Time Expended: $2000/24 hours = $83.33

Hourly Development Expenses per Instruction: $83.33 x 8 = $666.67
(Average hours to complete instruction)

Learner development expenses/hourly cost of instruction

$666.67/210 = $3.17

 

Chapter VI
CONCLUSIONS AND RECOMMENDATIONS

 

The purpose of the main study was to explore the possibility
of introducing audiovisual self-instructional modules in a Brazilian
agricultural engineering college in place of the traditional lecture
method.

0n the basis of the results of the main study, the following

conslusions were reached:

6.1 Conclusions

 

CONCLUSION l: Audiovisual instruction can be more effective than
traditional instruction in teaching agricultural
topics in developing countries.

 

On Objectives 1 and 2, students who were exposed to the revised
audiovisual module (used for teaching facts and concepts) performed
statistically significantly better than those exposed to the tradi-
tional lecture. This result contrasts with the HETZEL (1979) module
tested with American students which showed no significant differences
between audiovisual and traditional methods. Therefore, it would
appear desirable to continue gradual introduction of audiovisual

instruction into Brazilian agricultural engineering colleges.

CONCLUSION 2: Used with Brazilian students, the revised audio-
visual module results were, in general, better
than the results obtained in the pilot study
with the original audiovisual module.

101

 

102

After comparing the results of Objectives 1 and 2 in both the
pilot and main studies and the attitudinal response of the Brazilian
students, it was clearly evident that the revised module was superior
to the original module developed in the U.S. It would appear, there-
fore, that efforts to adopt materials developed in the U.S. for use
in developing countries would be more effective if the U.S. materials
were tried out in the developing country and appropriate modifications
.made.

CONCLUSION 3: Audiovisual materials, in order to be effective
in deve10ping countries, must be designed in
accordance with a systematic design process,
incorporating the seven characteristics of well-
designed instruction, and must include a cross-

cultural adaptation, based on a pilot tryout with
representatives of the target population.

 

Data from the pilot and main study showed that the revised audio-
visual module was considerably better than the original version. The
main changes between the original and revised versions were: (1) the
use of a systematic design process; (2) incorporation of seven charac-
teristics of well-designed instruction; and (3) a cultural adaptation
for the Brazilian students.

CONCLUSION 4: Audiovisual instruction can be more cost-
effective than traditional instruction in

teaching technical subjects in developing
countries.

 

The cost effectiveness of audiovisual instruction was $0.42 less
per student per instruction hour than traditional instruction. Further-
more, the cost effectiveness of audiovisual instruction will increase
over subsequent years as increasing numbers of students are taught
by the audiovisual method. The traditional cost would be, of course,

increased by inflation problems or other factors.

103

6.2 Recommendations

 

Based on the findings of this study, the following recommenda-

tions are made for future research and development with regard to

the audiovisual self-instruction method for use in courses offered

by agricultural engineering departments. Research needs to be conducted

to:

Determine those courses in the agricultural engineering
department that have the need and prerequisite require-
ments for an audiovisual self-instruction method.
Replicate this study in different disciplines in
developing countries.

Gain acceptance among faculty for use of audiovisual
modules.

Determine those factors which would make the use

of the audiovisual learning center be more favorable

to agricultural engineering students.

Determine the optimum class size to allow students to
learn by group audiovisual mode.

Determine the effect of the audiovisual self-instructional
module used as an introduction to lab-class.

Determine the changes in study behaviors by Brazilian
students who have used audiovisual self-instructional

methods.

BIBLIOGRAPHY

 

BIBLIOGRAPHY

 

Abedor, A. J., 1971. Development and Validation of a Model Expli-
cating the Formative Evaluation Process for Multi-Media Self-
Instruction Learning Systems. 'Ph.D. Dissertation, Michigan
State University, East Lansing, MI.

Abedor, A. J., 1978-1979-1980. A Handbook for the Design, Production
and Evaluation of Self-Instructional Modules. Learning and
Evaluation Services, Michigan State University, East Lansing, MI.

Abedor, A. J., 1979. A Handbook on Course and Lecture Design. Learn-
ing and Evaluation Services, Michigan State University, East
Lansing, MI.

Alexander, L. T., Davis, R. H. 1977. Choosing Instructional
Techniques: Guides for the Improvement of Instruction in Higher
Education. Michigan State University, East Lansing, MI.

Alderman, D. L. 1978. Evaluation of the TICCIT CAI System in the
Community College. Final Report, Vol. 1. Princeton, N.J.:
Educational Testing Service.

Allen, W. H., Cooney, S. M.; and Weintraub, R.. 1968. Audio Implemen-
tation of Still and Motion Pictures. Los Angeles: Research
Division, Department of Cinema, University of Southern Califor-
nia, CA.

Baker, E. L. and Popham, W. 1965. Value of Pictorial Embellishments
in a Tape-Slide Instructional Program. Audio-Visual Communica-
tion Review 13: 395-404.

Blaney, J. P. and McKie, D. 1969. Knowledge of Conference Objectives
and Effect upon Learning. Adult Education 19: 98-105.

Bloom, B. S. 1976. Human Characteristics and.SChool Learning. McGraw-
Hill Book Co., New York, N.Y.

Bloom, B. S. 1968. Learning for Mastery. UCLA-CSEIP Evaluation
Comment. Vol. I, No. 2.

Bolvin, J. 0. 1968. Implications of the Individualization of Instruc-

tion for Curriculum and Instructional Design. Audiovisual
Instruction 13(3): 238-242.

104

105

Brainard, A. J. 1975. Contemporary Education Challenges. American
Society for Engineering Education, Washington, D.C., 387-390 p.

Briggs, L. J. 1970. Handbook of Procedures for the Design of In-
struction. American Institute for Research, Pittsburgh.

Clark, R. E. 1980. 00 Students Enjoy the Instructional Method from
Which They Learn the Least?: Antagonism Between Enjoyment and
Achievement in ATI Studies. Paper presented at the Annual Con-
vention of the American Educational Research Association in Boston,
Massachusetts.

Connaly, J. J., and Sepe, T. 1972. 00 Students Want Individualized
Instruction. UCLA Eric Clearing House for Junior College Infor-
mation, No. 34.

Cooper, Terance H. 1975. Evaluation of an Audio-Tutorial Mastery
Learning Program in Soil Science for Agricultural Technology
Students. Unpublished Doctoral Dissertation, Michigan State
University, East Lansing, MI.

Dalis, G. T. 1970. Effect of Precise Objectives upon Student Achieve-
ment in Health Education. J. Exp. Educ. 39: 20-23.

Davis, R. H., Alexander, L. T., and Yelon, S. L. 1974. Learning
System Design: An Approach to the Improvement of Instruction.
McGraw-Hill Book Co., New York, N.Y., 342 p.

Davis, R. H., and Alexander, L. T. 1977. The Lecture Method: Guides
for the Improvement of Instruction in Higher Education. Michigan
State University, East Lansing, MI.

Diamond, R. M. 1973. Individualizing Student Learning. pp. 142-146 in
Dyckman W. Vermilye, ed., Current Issues in Higher Education.
American Association for Higher Education, Washington, D.C.,

238 p.

Diamond, R. M., Eickman, P. E., Kelly, E. F., Holloway, R. E., Vickory,
T. R., and Pascorella, E. T. 1975. Instructional Development for
Individual Learning in Higher Education. Educational Technology
Publications, Englewood Cliffs, N.U., 189 p.

Dick, W., and Casey, L. 1978. The Systematic Design of Instruction.
Scott, Foresman and Company, Glenview, Illinois.

Dwyer, F. M., Jr. 1973. Effect of Method in Presentin Visualized
Instruction. A.V. Communication Reviews 21 (1973 : 437-451.

Educational Development Program. 1974. Education Development at
Michigan State University, East Lansing, EDP No. 6.

Flocker, W. J. 1972. A Video-audio Self-tutorial Approach to
Learning. J. Agron. Educ. 1: 13-16.

106

Foth. H. D. 1967. Structured Learning and Training Environments in
Social Science. Project Report No. 204, August. Educational
Development Program, Michigan State University, East Lansing, MI.

Gage, N. L., and Berliner, D. C. 1974-1977. Educational Psychology.
Chicago: Rand-McNally.

Gagne, R. M., and Briggs, L. J. 1974. Principles of Instructional
Design. Holt, Rinehart and Winston, Inc., New York, N.Y. 270 p.

Gibson, J. J. 1947. Education Motion Picture Testing and Research.
Army Air Force Aviation, Psychology Program Research Reports,
Report No. 7. Washington, 0.0.: Government Printing Office.

Goldschmid, B., and Goldschmid, M. 1972. Modular Instruction in
Higher Education: A Review. McGill University, Montreal
(Quebec).

Green, D. E., Stamp, D. L., Thomas, T. T. and Jarner, L. L. 1973.
Student Response to a Personalized Learning and Narcaded Tutorial
System (PLANTS). J. Agron. Educ. 2: 5-9.

Gropper, G. L. 1966. Learning from Visuals: Some Behavioral Considera-
tions. AV Communications Review 14: 37-69.

Hoban, Ch. F., and Van Ormer, E. B. 1950. Instructional Film Research:
1918-1950. Technical Report No. SDC 269-7-19. Port Washington,
New York: U.S. Naval Training Special Devices Center.

Hoban, Ch. F. 1964-1965. Determinants of Adult Enrollment in Tele-
vised College-Credit Courses. Part 0: Motivation, Resistance,
and Conclusions. Philadelphia: Institute for Cooperative Re-
search, University of Pennsylvania.

Holloway, R. L., and Robinson, 8. 1979. Locus of Control and Sex
Differences in Performance on an Instructional Task. Improving
Human Performance Quarterly 8(1): 42-52.

Hetzel, G. H. 1979. Systematic Approach to the Development of an
Agricultural Engineering Course. Unpublished Doctoral Disser-
tation, Michigan State University, East Lansing, MI.

Iverson, J. J., Vincet, J. F., and Bender, R. E. 1970. Student and
Program Characteristics of Technical Agricultural Programs in
Ohio. NC 86, College of Agriculture and Home Economics. The
Ohio State University, Columbus. p. 38.

Jenkins, J. R. and Deno, S. L. 1971. Influence of Knowledge and
Type of Objectives on Subject Matter Learning. J. Educ.
Psychology. 62: 67-70.

Johnson, S. R., and Johnson, R. B. 1970. .Developing Individualized
Instructional Material. Westinghouse Learning Press, Palo Alto,
CA. 100 p.

107

Juola, A. E. 1977. Properties of Different Types of Test Questions.
Paper No. 39. Learning and Evaluation Service, Michigan State
University. East Lansing, MI.

Keller, R. S. 1968. Goodby, Teacher .... J. Applied Behavior Analysis
1: 78-79.

Lambert, R. H. 1970. Teachers' Perceptions and Principals' Expecta-
tions for the Teacher's Role in Individualized Instruction. Ph.D.
Dissertation, Michigan State University, East Lansing, MI.

Lindenland, J. C. 1970. Audio-Tutorial Instruction -- What, Why and
How. Engineering Education 60(7): 759-761.

Lindenland, J. C. 1974. Audio-Tutorial Instruction at Purdue Univer-
sity. Pp. 103-113 in L. P. Grayson and J. M. Biedonbach, Eds.,
Individualized Instruction in Engineering Education, American
Society for Engineering Education, Washington, D.C. 166 p.

Lowson, T. E. 1974. Formative Instructional Product Evaluation In-
strument and Strategies. Educational Technology Publications,
Englewood Cliffs, New Jersey. ‘

Lumsdaine, A. A., and Gladstone, A. 1958. Learning from Films.
New Haven, Connecticut: Yale University Press.

Mager, R. F. 1962. Preparing Instructional Objectives. Fearon Pub-
lishers, Palo Alto, CA 60 p.

McCarley, W. W. 1969. An Experimental Study to Evaluate the Effec-
tiveness of an Individualized Instructional Method and Lecture
Discussion Method for Teaching Vocational Agriculture. Ph.D.
Dissertation, Michigan State University.

McVey, G. C. 1970. An Experimental Evaluation of the Effectiveness
of an Audio-Tutorial Method in Teaching Vocational Agriculture.
Ph.D. Dissertation, Iowa State University.

Michigan State University and Brazil (MEC) Project. 1976. Agricultural
Engineering Survey Team Report. Report No. 13, Michigan State
University, East Lansing, MI.

Miller, G. 1975. Utilizing New Audiovisual Resources. Agricultural
Education Magazine. 47.9.201, University of Arizona.

Morris, Ch. J. and Kimbrell, G. McA. 1972. Performance and Attitu-
dinal Effects of the Keller Method in an Introductory Psychology
Course. Psychology Record 22: 523-530.

Olson, L. A. 1977. Checkpoints for Good Test Items. Paper No. 49.
Learning and Evaluation Service, Michigan State University,
East Lansing, MI.

108

Drtigiesen, Leroy. 1954. The Relative Effectiveness of Selected Film-
Strip and Sound Motion Pictures in Teaching Soil Conservation
in Ninth Grade Social Studies Classes. Ph.D. Dissertation,
University of Nebraska, 1954.

Dtt, M. D. and Macklin, D. B. 1975. A Trait-Treatment Interaction in
Colle e Physics Course. Journal of Research in Science Teaching
12(12): 111-119.

Peterson, P. L. and Janicke, T. 1979. Individual Characteristics and
Childrens Learning in Large-Group and Small Group Approaches.
Journal of Educational Psychology 71(5): 677-687.

Postlethwait, S. N., Novak, J. and Murry, H. T., Jr. 1964. An Inte-
grated Approach to Learning. Burgess Publishing Co., Minneapolis.

Postlethwait, S. N., Novak, J. and Murry, H. T., Jr. 1971. The Audio-
Tutorial Approach to Learning: Through Independent Study and
Integrated Experiences, 3rd Ed., Burgess Publishing Company,
Minneapolis, Minnesota, 184 p.

Postlethwait, S. N. 1969. Teaching Tools and Techniques: An Audio-
Tutorial Approach to Teaching. Developmental Efforts in Indivi-
dualized Learning. Weisgeber, R. A., Ed., F. E. Peacock, Inc.,
Itasca, Ill.

Rios, J. A. 1971. The University Student and Brazilian Society.
Latin American Studies Center. Michigan State University. Mono-
graph Series No. 6, East Lansing, MI.

Ronzheimer, K. 1973. We Increased Instructional Efficiency with Self-
Instruction. Industrial Education 62: 129-132.

Rowsey, R. E. 1974. Audio-Tutorial Versus Conventional Lecture-Labora-
tory Instruction in a University Animal Biology Course. Paper
presented at the Research Technology in College and University
Teaching National Conference. Atlanta, Georgia.

Russell, J. D. 1974. Modular Instruction. Burgess Publishing Company,
Minneapolis, Minnesota. 142 p.

Salomon, and Kendall, 1976. Heuristic Models for the Generation
of Aptitude-Treatment Interaction Hypotheses. Review of Educa-
tional Research, 42(3), 327-343.

Silva (da), J. V. 1977. Higher Education and University Reform in
Brazil. The Latin American Studies Center. Michigan State Uni-
versity, East Lansing, MI.

Smith, I. M. 1968. Experimental Study of the Effect of Television
Broadcasts on the G. Courses in Engineering Science: Part I.
The Vocational Aspect 20: 78-85.

109

Smith, I. M. 1969. An Experimental Study of the Effect of Television
Broadcasts on the G. Courses in Engineering Science: Part 2.
The Vocational Aspects 20: 89-100.

Stephen, R. F. 1971. Student Behavior in A-T Instruction. Paper re-
sented at Int. A-T Congress, Purdue University.

Vernon, P. E. 1946. An Experiment on the Value of the Film and Film-
strip in the Instruction of Adults. British Journal of Educational
Psychology 16: 149-162.

Wispe, L. G. 1951. Evaluating Section Teaching Methods in the Intro-
ductory Course. Journal of Educational Research 55(3): 161-186.

APPENDICES

APPENDIX A

PRETEST -- AND -- POSTTEST

APPENDIX A
PRETEST -- AND -- POSTTEST

Multiple Choice Questions

 

For each of the following statements, choose the best answer(s) and

mark the appropriate letter on the answer sheet.

1. Which implement(s) is commonly used in a primary tillage operation?

(a) Chisel plow

(b) Moldboard plow
. (c) Disk plow

(d) All the above

2. The angle or slope of the furrow slice is influenced by:

(a) The weight of the moldboard plow
(b) The ratio of depth to width of cut
(c) Type of soil

(d) All the above

3. We can modify the width of cut a small amount in a mounted
moldboard plow by adjusting the:

(a) Speed of plowing
(b) Left hitch point
(c) Right hitch point
d) Both a and b

4. The major effect of an incorrect level adjustment of the mold-
board plow is on:

(a) Traction of the tractor
(b) Depth of plowing

(c) Width of cut

(d) All the above

110

10.

11.

111
With adjustment of upper hitching link we get:

(a) Adjustment of width of cut

(b) Correction of the transversal level
(c) Adjustment of depth of cut

(d) Correction of length-wise level

.Which of the following parts of the moldboard plow is

responsible for the horizontal cut of soil:

a) beam

b) share

(c) land-side

(d) moldboard plow

In order to choose the right size and curvature of moldboard,
we need to take in mind:

(a) the traction force
(b) the conditions of soil and speed of works
(c) the angle or slope of the furrow slice

. (d) none of the above

Which part(s) of the moldboard plow is responsible for the pulveri-
zation and overturn of the furrow slice:

(a) the front part of the share

(b) the top part of moldboard

(c) the central part of the moldboard
(d) both b and c

On which part of the moldboard plow do the horizontal and vertical
suction occur?

(a) share

(b) land side

(c) moldboard

(d) rear furrow wheel

The length of the landside depends on:

a) If the moldboard plow has rear wheel
b) Texture of the soil

(c) Moisture of soil

(d) Size of moldboard plow

The safety shear pin of the moldboard plow is located on the:

(a) moldboard (c) beam
(b) landside (d) a and b

12.

13.

14.

15.

112

The rolling coulters must be adjusted with which of the follow-
ing in mind:

traction force
depth of plowing
width of plowing
soil conditions

The location of the center of load (resistance) for a single
bottom plow will be:

(a)

approximately one-fifth the width of cut from the
furrow wall '

approximately one-fourth the width of cut from the
furrow wall

approximately one-half the depth of cut

both b and c

The weight transfer in the mounted and semimounted plow increase
traction the following way:

by adjustment of the moldboard plow

weight transfer from the tractor on moldboard plow
weight transfer from the plow on the tractor rear wheels
weight transfer from the front wheels on the rear wheels
of the tractor

The reversible moldboard plow will be recommended to work
fields with:

regular shape

flat land

hilly land and irrigated land
all the above

APPENDIX B

STUDENT QUESTIONNAIRE

Appendix B
STUDENT QUESTIONNAIRE

NAME ' ' DATE

 

 

LESSON

 

Please be frank and honest in answering the following questions. Remem-
ber you are our prime source of information regarding what needs to
be revised.

KEY: SA means strongly agree; A means you agree; U means you are un-
certain; D means you disagree; and SD means you strongly disagree.

1. I had sufficient prerequisites to prepare SA A U D SD
me for this lesson.

2. I was often unsure of what, exactly, I SA A U D SD
was supposed to be learning.

3. Listening to the tapes and watching the SA A U D SD
slides was often boring.

4. This lesson was well-organized. The SA A U D SD
concepts were highly related to each other.

5. There was too much information. SA A U D SD

6. There was too much repetition of ideas. SA A U D SD

7. There was very little unnecessary information SA A U D SD
in this lesson.

8. Often the tape and slides seemed unrelated SA A U D SD
to each other.

9. The examples used to illustrate main points SA A U D SD
were excellent.

10. The vocabulary used contained many unfamiliar SA A U D SD
words. I often did not understand what was
going on.

11. The pre-test and final exam questions did a SA A U D SD

good job of testing my knowledge of the main
points in the lesson.

113

 

12.

13.

14.

15.

16.

17.

114

Many of the thingsI was asked to do, or SA
questions I was asked to answer during
the lesson seemed like needless busy work.

At the end of the lesson I was still un- SA
certain about a lot of things and had to
guess on many of the post test questions.

I believe I learned a lot, considering the SA
time spent on this lesson.

I would recommend extensive modifications SA
to the lesson before using it with other
students.

After completing the lesson, I was more SA
interested in and/or favorably impressed

withthe general subject matter than I

was befOre the lesson.

SD

SD

SD

SD

SD

Please write below any comments, suggestions, or changes which you

believe will improve this lesson. Thank you.

 

APPENDIX C

SUMMARY OF COMMENTS FROM OPEN-ENDED QUESTION
(PILOT STUDY)

 

APPENDIX C

SUMMARY OF COMMENTS FROM OPEN-ENDED QUESTION
(PILOT STUDY)

Item 17: Please write below any comments, suggestions or changes
which you believe will improve this lesson.

Audiovisual Instruction

 

 

I considered the use of slides a good idea but the duration
of the presentation must be increased.

I like the slide presentation and I suggest that you improve
the narration (quality of sound).

I found the audiovisual class one of the best classes I had,
but the vocabulary level was too high.

I like the slide presentation.

I found it to be an excellent system of instruction but too
saphisticated for our conditions.

I felt the slide-tapes were a very good learnin experience.
Improve the narration (length and sound quality).

I like the slide tapes, but I consider the narration to be
too fast.

I believe I learned a lot from the audiovisual method but I
felt there were too many things to learn in too little time.

I really enjoyed the audiovisual method - I suggest that you
correct the time of presentation (more time).

I was distracted by the English legend - I hope it will be
changed to Portuguese.

I liked the slides but slower narration is necessary.
I found the method too complicated. I need more time to learn.

The method gave me a good overview of the topic but need
improvement (narration and time).

115

116
I found it to be too many topics for one class. Use Portuguese
for slide legends.
Too much information, but I liked the class.

I found the method (audiovisual) very valid. Improve sound
and diction.

APPENDIX D

NORKSHEETS

’WORKSHEET 1

 

 

 

EIGWSK 1: ‘ NAME
ETERMINE RATIONALE (NEED
OR & FEASIBILITY OF) DATE

 

ELF-INSTRUCTIONAL MODULES_
TITLE OF COURSE
A. STUDENTS:

1. NUMBER AND CHARACTERISTICS

B. THE COURSE CONTAINS SUBJECT MATTER WHICH IS: (circle)
TAUGHT REPETITIVELY
STABLE FOR 2-3 YEARS
DIFFICULT TO TEACH "LIVE" GROUPS

PRESENTABLE IN 30-45 MINUTES
DOES NOT ABSOLUTELY REQUIRE FACE-TO-FACE INTERACTION

mth—J
. O C

C. THE SELF-INSTRUCTIONAL MODULES WOULD BE USED AS: (circle)

THE SOLE SOURCE -

THE PRIMARY SOURCE OF INSTRUCTION

A SUPPLEMENT OR ENRICHMENT TO OTHER FORMS OF INSTRUCTION
PREPARATION FOR DR PREREQUISITE TO OTHER INSTRUCTION

AN EQUIVALENT ALTERNATIVE TO OTHER INSTRUCTION

mth—a
o o a o I

D. RESOURCES AND CONSTRAINTS

1. MONEY
2. TIME
3. FACILITIES
4. PERSONNEL

E. RATIONALE §STATE WHY AND HOW YOU INTEND TO USE SELF-INSTRUCTIONAL
MODULES

117

118

 

 

 

 

_ Nmmfinz ..
ESIGN TASKS NAME
8 3:
RITE MODULE OBJECTIVES DATE
ND WRITE CRITERION SELF-TESTS

 

TOPIC OR TITLE OF MODULE"

 

 

GENERAL GOAL 0F MODULE

 

MODULE OBJECTIVE 1:

 

 

CRITERION SELF-TEST:

Write the actual test item(s), including instructional to the student,
that you would use to assess whether the student had achieved the
objective(s) above.

 

 

 

 

 

 

TYPE OBJECTIVE ( )RECOGNITION ,(,)RECALL[PRODUCTION ,( )APPLICATION

 

 

CRITERION ( ) MULTIPLE (E) SHORT ANSWER ( ) PROJECT

TEST CHOICE ( ) WRITTEN ESSAY OR ( ) SIMULATION

FORMAT ( ) TRUE-FALSE SOLUTION TO ( ) JOB PERFOR-
(,) MATCHING PROBLEM NANCE

( ) ORAL

 

 

 

 

 

119

 

 

 

 

 

‘WDRKSHEET'B
DESIGN TASK 4: NAME"
Outline Module DATE '
Content

 

 

FOR EACH OBJECTIVE IN YOUR MODULE, LIST IN OUTLINE FORM THE MAIN

POINTS, TOPICS, FACTS, CONCEPTS, PRINCIPLES, OR SKILLS THE STUDENTS
MUST LEARN IN ORDER TO ACHIEVE THE OBJECTIVE. DO NOT WORRY ABOUT THE
SEQUENCE OR RELATIVE IMPORTANT OF THE TOPICS LISTED. JUST BRAINSTORM
FOR A WHILE UNTIL YOU ARE RELATIVELY SATISFIED THAT MOST OF THE TOPICS
ARE LISTED. THE NEXT STEP (ON WORKSHEET 4 ) WILL BE TO RESEQUENCE THESE
TOPICS IN THE ORDER OF PRESENTATION.

OBJECTIVE 1 TOPICS OBJECTIVE 2 TOPICS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

120
WORKSHEET'4

 

DESIGN TASK 4 NAME
Sequence Content DATE"'

 

RECALL THE TWO TYPES OF ORGANIZATIONAL STRATEGIES (INDUCTIVE AND DE-
DUCTIVE) AND THE FOUR ALTERNATIVE SEQUENCING TYPES: (1) HIERARCHICAL;
(2) CHRONOLOGICAL; (3) SPATIAL; AND (4) SPIRAL. SELECT AN INDUCTIVE

OR DEDUCTIVE STRATEGY AND ONE OF THE SEQUENCING ALTERNATIVES AND REWRITE
THE CONTENT OUTLINE IN THE SELECTED SEQUENCE.

OBJECTIVE I TOPICS OBJECTIVE 2 TOPICS
(in sequence) (in sequence)

 

 

DESIGN TASK 5
SELECT FORMAT
AND TREATMENT

 

 

( ) EXPOSITION

 

( ) individual
talk
( ) group talk

( ) talk plus
visuals

( ) stills
( ) motion
( ) demo
( ) drama
(

) off-camera
narration

vvvvvvvvv

121

WORKSHEET 5

NAME“"'
DATE

 

TYPES OF TREATMENT

 

 

 

 

 

 

DEMONSTRATION ( ) DRAMATIZATION ( ) COMBINATION
simplified ( ) abstract or ( )

real life ' ( ) realistic

"expanded"

51°" motion ( ) fictional or

stop motion documentary

ECU/MACRO

animation ( ) humor

other ( ) satire

 

Describe the treatment to be employed

 

 

 

What is the rationale for using this treatment?

 

 

 

What format will be employed? Why?

.audiovisual (

) .

. (. ) print . ( ) combination

 

 

 

 

 

 

APPENDIX E

MODULE 1
USING THE MOLDBOARD PLOW FOR TILLAGE

 

 

M O D U L E 1
Using the Moldboard Plow for Tillage

Welcome to the lesson: Using the moldboard
plow for tillage. This lesson was developed
by Professor MAURO MEZA MONTALVO from the
Federal Rural University of Rio de Janeiro.
During this lesson you will learn several
things.

First: You will learn the main parts and
function of the moldboard plow and its
attachments.

Second: You will be able to describe the
mechanical action of the moldboard plow
bottom and its attachments.

Third: You will be able to identify the
forces acting on the plow and determine the
center of load. The first two objectives

will be accomplished through use of this audi-
visual lesson. The third objective will be
achieved by means of the audio-visual lesson
and your lab class.

122

‘m

 

123

For you to achieve these objectives certain
prerequisites are necessary. First, you should
be able to describe the purpose of tillage
operation. Second, you should be able to recog-
nize the chisel plow, moldboard plow, and disc
plow. If you do not have these prerequisites
contact your instructor before going on with
this lesson.

We will begin by learning the main parts and
functions of the moldboard plow.

The moldboard plow is one of the most important
and popular pieces of implements used in
the tillage operation.

The main parts of the moldboard plow are
identified as follows:

(1) Beam (4) Share

(2) Frog (5) Moldboard

(3) Landside

The share is the horizontal cutting edge of
the moldboard plow. It is located on the
front lower edge of the bottom.

 

 

 

USO GERAL

 

124

There are several types of shares depending
mainly on the types of bottom and the types
of soil.

(a) full cut--general conditions

(b) narrow cut--hard soils--no roots

(c) heavy duty--story--rocky soil

(d) hard surface--abrasive soil

(e) sod bottom share--hard to scour soil

The moldboard is the curved part of the
bottom, located above the share. It turns
and breaks the furrow slice. There are many
types and shapes.

PLOW BOTTOM DESIGN
General purpose
High speed
Slatted
Stubble
Scotch
Deep tillage

The general purpose bottom is widely used.
It gives a slow turning action to the furrow
slice at plowing speeds of 3 to 4 miles per
hour. It may be used in heavy soils, sod,
or stubble ground.’

 

125

The high speed bottom has less curvature than
the general purpose bottom. It is designed
for plowing at higher speeds, 4 to 7 miles per
hour, and thus has less twisting action built
into the moldboard.

The slatted bottom has strips of the moldboard
removed. This increases the soil pressure
against the remaining portions of the moldboard
and aids in scoring when plowing sticky soils.

The stubble bottom moldboard is short, high,

and has an abrupt curvature. It turns the
furrow slice quickly and provides maximum granu-
lation. It is used in plowing stubble land

and is not suited for high-speed plowing.

The scotch bottom moldboard is used in heavy
soil. The furrow slice is not pulverized, but
is turned on its side and exposed to air and
weather effects.

 

 

 

126

The semi-deep bottom has a high moldboard to
permit plowing as deep as 16 inches in heavy
soil. It is used mainly in irrigated areas.

Another important part of the moldboard plow
is the landside. This is a flat horizontal

piece bolted to the frog and it runs against
the furrow wall. It absorbs side forces and

helps keep the plow straight behind the tractor.

Landsides are available in various lengths for
different applications. The landside shown
here is 14 inches long and equipped with a
replaceable chilled heel. It is intended

for use in abrasive soils.

This landside is 20 inches in length and
equipped with a chilled heel. It is designed
primarily for mounted plows which are not
equipped with a rear furrow wheel. It pro-
vides support for uniform plowing.

1| dilnln.)

127

21 A rolling landside may be used in addition

to the flat landside on some mounted plows.
It is positioned on an angle to the furrow
wall so it can absorb side loads.

 

 

 

 

The frog provides the foundation and support
for the bottom and all parts are attached to
it. The frog also gives the plow bottom its
wedge shape.

 

Lastly the beam or frame holds the plow bottom
in the correct position relative to each other.
~The frame is bolted to the frog and transmits
power from the tractor to the plow bottom.
Answer the questions and refer to work-sheet
number 1, following the instructions.

 

 

The next part of this lesson concerns identi-
fying the moldboard flow attachments.

 

. Rolling Coulters . Moldboard
. Disk Coulters . Roof Cutters
. Trash Boards . Weed Hooks

. Jointers . Gauge Wheels

 

 

26

 

 

128

Here is a diagram showing a rolling coulter

in front of the moldboard plow. The rolling
coulter cuts through surface trash and cuts

the furrow slice free vertically. This enables
the plow bottom to pull easier, plow cleaner
with less plUggings.

There are three types of rolling coulter blades:

(a) Plain - these blades are used where
trash is not excessive in quantity.

(b) Notched coulters are used in hard ground
and in heavy trash conditions.

(c) The fluted blade or rippled edge is
effective for cutting through trash.

Other attachments are seen in white:

- Trash boards - this aids in covering heavy
straw, stubble, or stalks.

- Jointers have a shape similar to a plow bottom
and are effective in standing trash conditions.
They turn a narrow ribbon of soil through the
coulter and aid in "clean" plowing.

- Moldboard extension-this applies to the furrow
slice and prevents its rolling back into the
furrow when plowing on hillsides.

Root cutter--they are attached to the plow bottom
for cutting alfalfa or similar roots.

-Weed hook--aids in plowing under tall growing
green materials.

-Gauge wheels may be used for extremely vari-
able plowing conditions on integral and semi-
mounted plows. They help to maintain uniform
depth of plowing.

Now refer to work-sheet number 2. Follow the
printed instructions and answer the questions.

.15.); up Sup-.1“

 

 

 

 

 

 

 

 

129

Having learned the main parts and attachments of
moldboard plow, you will now study the mechanical
actions of the plow bottom.

Section I describes the actions responsible for
the horizontal cut of the furrow slice.

Section II is the middle section responsible for
the pulverization of the furrow slice.

Section III is the upper section responsible for
the inversion of the furrow slice.

The moldboard granulates the soil gradually as
the soil moves along its curved surface. The
figure indicates the development of shear planes.

This granulation occurs as the plow moves for-
ward. The wedging action on the soil exerts
both upward and toward the open furrow. The
stresses set up by this action cause "blocks"

of soil to be sheared loose at regular intervals.

Final granulation or pulverization occurs when
the furrow slice leaves the moldboard and is
turned into the furrow.

O ANOULO DE TWIAMEN‘I’O

80H TOMBAMENTC

 

 

 

130

Another interesting point is that the angle
of the furrow slice is influenced by several
factors:

- speed of plowing

- curvature of moldboard

- ratio to depth and width

- levelness of plow

The best slope of the furrow slice is approxi-
mately 50 degrees; it is obtained by having:

- the correct speed

- the plow correctly adjusted

- the right type of moldboard

- having the plow cutting the proper width in
relation to depth

A furrow slope which is too upright, 70 degrees,
may be caused by:

plow speed too low

plow running "on its noise"

lack of curvature in moldboard

plow cutting narrow in relation to depth

A furrow slope which is too flat may be
caused by:

- plow speed too high

- excessive curvature in moldboard

- plow wing over to plowed land

- plow cutting too wide in relation to depth

 

£1.55.

 

 

 

 

 

 

131

Some other adjustments that will effect the plow
operation are: LEVELNESS

Operating a plow bottom out of level will cause
either too much or too little pressure being
exerted on the furrow slice. The results will
be poor granulation.

When the plow is running perfectly level, the
granulation and the traction are ideal.

When the plow is running on its noise, pressure
is released from furrow slices too quickly,
which results in poor granulation.

When the plow is winged over to plow land, the
results are excessive pressure on the lower
part of the furrow slice and gives poor plowing.

 

 

132

To complete our understanding of the forces
acting upon the plow bottom we must consider
the clearance shown in the figure called
suction. There are two types: side and down
suction, that produces a plow action with a
uniform width and depth of cut.

The side suction has 1.5 to 6 mm of clearance.
This helps to neutralize the side forces and
maintain a uniform width of cut for the furrow
slice.

The down suction has 3 to 9 nm (millimeters) of
clearance. This helps to neutralize the
vertical forces coming from the soil to the
bottom and improves plow penetration. Now,
stop and answer the questions, on work-sheet
number 3. Please follow the printed instruc-
tions.

The last objective of this lesson is to prepare
you for the lab-class, by teaching you to reor-
ganize the forces acting on the plow bottom
and the resultant center of load.

 

 

133

45 There are several forces of components of resis-

- H1 Soil resistance

- V2 Reaction force of the soil upon the
barrow part of the bottom

- H2 ReactiOn force of the soil upon the !
landside. ;

 

 

 

 

 

 

 

- wrflfl_ 46 There are two component forces of the draft or 1
‘ g power: _J
E - L Force of pu11 ‘
i E") - V] Weight of the plow
47 The center of load is the resultant point on the
moldboard where all the forces meet. Its approx-
imate horizontal location for a single bottom
plow is 1/4 of the width of the furrow cut mea-
sured perpendicularly to the land side.
48

The vertical location of the center of load is
THO one half the plowing depth. The cross point of
the horizontal and vertical location is the

 

center of load. The calculations of center of
load will be done in the lab class.

 

 

 

134

Review--During this audi-visual lesson you
learned:
- To identify the parts and functions of the
moldboard plow. Briefly these parts are:
share - moldboard - land side - beam - frog. h

You also learned the different events that occur
on the bottom of the moldboard plow. You recall
those events were:

- cut - levelness

 

 

 

 

- pulverization - suctions
- overturn of the furrow slice

 

Finally, you learned the identification of the
forces and the location of the center of load
on the moldboard plow bottom.

 

,,SI_ ,T?_u In the next class we will study various types of
I .s TN moldboard plow and their adjustments.

 

‘- . I
$51!:
.. if.»

 

 

 

135

A thorough understanding of this subject will
help provide good understanding of the tillage
operation and give a basis for making a good
selection of a moldboard plow.

 

At this time, answer the questionnaire on page 4
of your workbook.

Thank you! END

 

APPENDIX F

SUMMARY OF COMMENTS FROM OPEN-ENDED QUESTIONS
(MAIN STUDY)

 

 

APPENDIX F

SUMMARY OF COMMENTS FROM OPEN-ENDED QUESTIONS
(MAIN STUDY)

Audiovisual Instruction

 

We need more classes such as this. I enjoyed the method.
I liked the slide tape more than the traditional class.

I consider it to be a good innovation of instruction, I needed
to see the slides one more time.

I need additional information from the instructor or to see
the slides more slowly.

I learned a lot, in little time.

I consider it to be a wonderful idea: I suggest that you correct
the narration.

I like the class very much. It was good experience.
Create more modules.
I suggest that you offer less information. Good idea.

I liked the slide outfit. I suggest that you improve the
narration and length of presentation.

I was surprised how well one can learn without an instructor.

136