Annotations for Defining Interactive Instructions to Interpreter Based Program Visualization Tools

An interpreter based visualization tool can be used for creating visualization exercises that engage the student to work with the visualization instead of just watching it passively. This article describes how to make the interpreter instruct the student interactively. The idea is to use the interpreter for testing the code that the student has written and give the instructions according to the test results. This only requires minor work for implementation of the visualization tool.