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The expression evaluation in C, C++, and Java is one of the most difficult to understand topics. Students have problems with both understanding the order of operator execution and understanding the semantics of operators. To help the students, we have developed WADEIn system (Brusilovsky & Su, 2002). WADEIn allows students to explore the process of expression evaluation step-by-step with detailed visualization. It also helps them to check their understanding of the order and results of evaluation. From research point of view, the goal of WADEIn is to explore adaptive and engaging visualization (WADEIn does not use explanatory visualization). WADEIn works in both exploration and evaluation modes.

In exploration mode (see screenshot to the right) the student can visually observe the process of evaluating C expressions. The level of detail in executing an operation depends on the useršs current level of knowledge about it. For the minimal level of knowledge the system visualizes all sub-steps and shows the animation in a slow motion. As the user learns an operation increasingly better and his or her knowledge level improve, the system degrades gracefully the level of detail in the visualization by increasing the speed of animation and removing sub-steps.

The evaluation mode provides a way to better engage students as well as to evaluate their knowledge. Here the students have to predict the correct order of execution and the result of each operation that has not been mastered according to the student model. We have used WADEIn in classroom for 6 semesters. Our recent questionnaire filled by 29 students who have tried from 20 to 441 WADEIn shows that more than 80% students found WADEIn system and its adaptive visualization helpful or very helpful.

This project is currently supported by NSF Directorate on Computer and Information Science and Engineering through Award #0426021

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.



Š 2002 School of Information Sciences, University of Pittsburgh
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Tel: 412.624.5230, Email: inquiry@mail.sis.pitt.edu
Last updated 2006-04-04