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.
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.