Chemistry On-line Homework System
INTRODUCTION
Homework is a well-established pedagogical tool used to motivate students
and to focus their study on particularly important concepts. It can also
be used to provide students feedback on their progress, to help instructors
evaluate student learning, and to provide information to instructors about
misconceptions commonly held by the class as a whole. Recently, there has
been a rapid expansion in the availability of software and Web-based tools
for use by educators wishing to improve student learning. Such uses include:
on-line lectures, electronic discussion forums, e-mail, interactive CD-ROM
textbook supplements and exercises and questions in the form of homework,
quizzes and exams.
Homework, while widely accepted as a valuable learning tool, does have
its weaknesses. Because homework is done outside of the classroom setting,
there is little control over the possibility of students copying assignments
and sharing answers. While this Acooperative
learning may be an effective
learning approach, it is not very useful to the instructor for evaluating
student performance or uncovering common misconceptions. Furthermore, generating
homework questions, grading homework assignments and analyzing the results
is often a very time consuming process for instructors. Finally, for students
there is often too long of a turn-a-round time between submitting their
work and getting feedback. In an effort to overcome many of these shortcomings,
we have designed an on-line homework system for use in General Chemistry.
The prototype
system currently provides for the individualized on-demand generation
of conceptually based homework questions with immediate feedback for student.
The complete system will incorporate automatic grading and record keeping,
tutorial feedback for the students, and feedback to the instructor about
common misconceptions held by their students.
CHEMISTRY HOMEWORK MODELS
Chemistry exercises often tend to be of two types: algorithmic or conceptual.
Algorithmic, or quantitative, exercises are usually calculations based
on equations and formulas. Because these exercises often can be done successfully
without students really grasping the underlying principles behind the equations
and formulas, they are sometimes referred to as "plug and chug" exercises.
Algorithmic exercises have the advantage that they are often easy to formulate.
On the other hand, conceptual exercises, which require students to analyze
and interpret diagrams, graphs, and verbal explanations and to construct
mental "pictures" to explain the observed phenomena, are often more difficult
to generate. Hybrid exercises, which require students to generate the desired
equations and formulas from their own conceptual understanding, can provide
powerful learning opportunities. While equation based exercises are widely
used and certainly have their value, there is currently a major effort
in the teaching of general chemistry to include more conceptual and hybrid
approaches[1, 2, 3].
CURRENT COMPUTERIZED APPROACHES
In recent years, several computer based chemistry homework/quiz systems
have become available including Chemskill
Builder, Falconware,
and OWL. These systems
are a major step forward in computerized homework for general chemistry
and overcome many of the weaknesses of the conventional homework approaches
mentioned earlier. However, they generally suffer from one of two shortcomings:
1) they tend to be primarily algorithmic in nature, which provides for
the possibility of "plug and chug" or 2) they have a limited number of
questions covering each concept area, and students, through the use of
"trial and error" runs, can quickly cycle through the entire question bank
and learn" the correct answers for each question without actually understanding
the underlying concept
A REVISED APPROACH
The advantages of the systems currently available, along with their limitations,
provided the motivation for this project, which is to develop an on-line,
conceptually based, individually generated homework system for general
chemistry . The project has the following goals:
Conceptually Based - Start with the concepts first, and then generate
the equations and formulas - i.e., not just "plug and chug."
Individually Generated - Generate questions based on the same concept
and at the same level of difficulty, but each set of questions is unique.
On-line, Web-based - Take advantage of the pervasiveness of the Web
for broad distribution and easy accessibility, as well as for ease of collecting
and analyzing results.
Computer Graded - Developed to provide direct and immediate feedback
to students as to their progress and to reduce the instructor time commitment
as much as possible.
Practice and Evaluation modes - Provide a formative mode for students
to use the system interactively as they learn the concepts, as well as
an evaluation mode for instructors.
A prototype of this system uses question templates as a means of generating
thousands of unique, but comparable, questions for a given concept area.
The focus has been on two topic areas within general chemistry: calorimetry
and solution concentrations. In addition to generating the questions, the
prototype program generates a set of multiple choice answers, one that
is correct, and several incorrect "distracters" which are generated by
anticipating likely student misconceptions.
The key to the generation of the templates for these questions is the
knowledge extraction process that transfers knowledge from a domain expert
(in this case, the chemistry professor) to a computer program. In the extraction
process, the program developers identify the root concept, isolate the
key issues involved with the concept, identify likely misconceptions and
identify constraints. In addition, any data, charts, graphs, conceptual
images, etc., that are needed are defined. The programmer then identifies
the variables for the questions, which can include generated numbers, formulas,
equations, chemical elements, selection of charts or graphs and relational
parameters such as high, low, most, least, same as, and less than. From
these variables, rules for the generation of the question, the correct
answer, and the distracters based on the misconceptions, are developed.
In the prototype implementation, several types of questions can be generated
with literally hundreds of thousands of variations, virtually guaranteeing
that no two students in a class will see exactly the same question.
FUTURE EXTENSIONS
When completed, the overall on-line homework system will include: 1) a
database management system that will store the information (variables,
rules, etc.) for each question type and corresponding answer generation,
as well as student records; 2) an analysis mode that will capture and summarize
the results of the student work and help the instructor uncover common
misconceptions; 3) a tutorial mode that will provide instructional feedback
to students that addresses the misconception related to the distracter
selected; and 4) a question authoring module to streamline the question
development process. In the future this system will be generalized to apply
to disciplines other than general chemistry. In other words, the long-term
goal of this project is to develop a versatile on-line homework system
that can be used easily and effectively to enhance student learning in
many disciplines.
REFERENCES
1) Lloyd, R. J., and Spencer, J. N., J. Chem. Educ., 1994, 71(3),
206-209.
2) Ward, R. J., and Bodner, G. M., J. Chem. Educ., 1993, 70(3),
198- 199.
3) Nakhleh, M. B., and Mitchell, R. C., J. Chem. Educ., 1993,
70(3), 190-192.