AN EVALUATION OF INTRODUCTION TO COMPUTER SIMULATION:
THE SYSTEM DYNAMICS APPROACH
. Nancy Roberts
Graduate School of Education
Lesley College
Cambridge, Massachusetts
Introduction
With the goal of introducing system dynamics to high school students,
a set of six learning packages were written during the 1979-80 academic year
under Grant Number G0D7903439 from the US Office of Education. Co-authors of
the material are Nancy Roberts, David Andersen, Ralph Deal, Michael Garet,
and William Shaffer. The evaluations from pilot testing done during the
grant year in six Greater Boston high schools suggest that the materials
indeed can effectively accomplish this introductory role. The teachers
involved generally made very positive comments about both the value of
system dynamics as an exciting high school subject as well as the 4ppropriate-
ness of the particular materials. [1]
This past year the authors have been negotiating with publishing
companies for the publication and distribution of the materials. In addition,
several other people have used the new curriculum, This paper attempts to
of the materials as well as
summarize the evaluation of this past year's u
to describe the form in which they will be published by Addison-Wesley.
Selected Case Studies
Groton School. A physics and a mathematics teacher from the Groton
School, an independent high school in Groton, Massachusetts, used the
materials to create a new two-year applied mathematics curriculum for junior
and seniors. The two year sequence is equivalent to three years of high
303
-2-
school mathematics. The course is open to anyone who has completed a
pre-calculus course.
The course begins with an introduction to computer programming in
BASIC using Apple II microcomputers. System dynamics is next introduced.
The students are taken through the learning package materials up to and
including the first full model in package six, the Kaibab Plateau Model.
The SYSDYN Package, a BASIC program that allows students to write cable
functions and get plotted outputs for their models, is used. The rest of the
first year consists of teaching differential calculus, an introduction to
Probability’and statistics, and an introduction to integral calculus. The
final project of the first year is the Flu Epidemic Model, the second modelling
exercise in package six.
The second year consists of linear algebra, enough calculus to
complete the CEES BC calculus syllabus, and an introduction to differential
equations. In addition, a minimum of one more system dynamics model fren
package six is covered.
The Groton course in applied mathematics is held together by system
dynamics. First, system dynamics gives students some powerful problem solving
techniques. Second, it serves as an excellent introduction to mathematical
modelling. Third, the concepts of rates and levels pave the way for
derivatives and integrations and for differential equations. Finally, systen
dynamics gives students gome concepts, problem solving strategies, and
mathematical skills that can be used in many other disciplines at Groton.
Simon's Rock. The learning pachages were used in a course called
System's Seminar, a required course for juniors or seniors who are either
environmental or computer science majors. This course was also taught using
BASIC because DYNAMO is not available for the Digital Equipment Corporation's
om
PDP8. All but one of the students had some computer background. The student
who had no previous computer course had the most difficulty with the material.
The learning packages were the only text used in the course. The instructor
translated package V, “Introduction to Simulation", into BASIC. The students
through the first five learning packages and the Kaibab Plateau Model
in package VI in one term. The instructor found the packages to be "tremendous
teaching devices". The students found the materials clear and well written
even though they were obviously intended for a younger audience.
Boston University. Learning packages one through five were used
in 2 one tern, undergraduate introductory sociology course along with a
sociology text. The students worked through packages I to IV on their own.
When they got to package V, they were given a running model of the general
negative loop shown in Figure 1. Their assignment was to apply this general
nodel to a specific problem to which they personally could relate. Figure 2
is an example of a specific application of the general model.
= ¥
+
PROBLEM =) PROBLEM
SOLUTION DEFINITION
+
Figure 1. General Problem Statement
os ge STRATIFICATION:
a “yy
T 7) RELATIVE
DEPRIVATION
+
Figure 2. Specific Problem Statement:
One Person's Reaction to Another
304
ahe
The validity check was "Does the model output make sense in comparison to
what actually happens in your life?"
The evaluation by the professor was that system dynamics has the
potential around which to structure a whole undergraduate curriculum. In
fact, he is attempting to organize a faculty committee to consider just this.
He felt the learning packages as written were too repetitious for college
level use and could be tightened up considerably. Again, the students
running into difficulties were those with no previous computer experience.
‘MIT, The materials were used for a required course in the Sloan
Fellows Program, the middle management executive training program. Tne
materials were chosen for the course because the professor saw them as a
way to teach the Sloan Fellows to actually build system dynamic models. Fer
the past fifteen years only a small percentage of the class actually went on
to model building. The goal this year was to have the entire class get
through at least one modelling project in package VI.
Over..the years, most Sloan Fellows had seen little relevance to their
concerns of system dynamics, This feeling did not change this year. In
addition, except for the people from government agencies, the rest of the class,
primarily from industry, did not like these particular materials because:
1, the general subject matter of the examples was not on problens
relevant to them;
2. the underlying tone of the examples is ecological and environzental,
which, for the past ten years, has been perceived as ant{~industry preaching.
In spite of all these problems, the quality of the term projects vas
very good, with far more widespread accomplishment than in any other previous
year. In addition, the final tests demonstrated significant learning had been
achieved. Next year the semester-length course will become elective, with
several required introductory sessions as part of the Decision MUdels course.
The professor plans to use the materials again but because the class will be
self-selected, does not anticipate encountering the problems with subject
matter of the examples or relevance of system dynamics.
Revisions and Publication Plans
The six learning packages are being published as a college text by
the computer science division of Addison-Wesley. However, the book will
also be marketed by Addison-Wesley's high school division. Book distribution
and promotion will be coordinated with Addison-Wesley's production and
distribution of DYNAMO for the Apple IZ microcomputer. In light of the fact
that the primary audience ie now seen as college undergraduates, the following
revisions are being made by the authors:
1. The tone of the material is being changed. It will be more
formal in the language used and some of the repetition included for high school
students will. be eliminated.
2. The audience for book adoption has been reassessed as comprising
a wide range of faculty teaching in the social, policy, and administrative
sciences. There will be some changes in the subject matter of the exercises
and exanples to reflect the interests of this group.
3. More explicit discussion will be added throughout the text relating
system structure to system behavior. A new chapter is being written for
package V that will give students a series of small models chosen to illustrate
a variety of simple structures and their resulting dynamic behavior. Publication
date of both the book and the Apple II version of DYNAMO is scheduled for next
spring.
305
REFERENCE
1. Roberts, Ne “Developing An Introductory Curriculum in System Modelling
and Simulation: The System Dyaamics Approach’ Technology Forecasting
‘and Soctal Change, scheduled for publication, Fall, 198].
CC BY-NC-SA 4.0