Much work has been done on Software Visualization [Stasko et al 98]. John Stasko has experimented with providing students with visualization software and having students write code for algorithm execution and visualization using his graphics libraries. [Stasko 90, 97] Students must learn commands that are outside their programming language environment and use software that is a bit like a 'black box'. Changes to source code will not be reflected in visualizations without explicit changes to the visualization calls.