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.