Something where somebody can scribble lines and as the lines "age" they grow/bleed would be neat. Maybe something that changes colors as you draw. This could also teach structure and algorithms a bit as you have to model the drawing as an abstract concept instead of just pixels. OR the pixels could be the model and change algorithmicly so that as you draw the colors of existing pixels rotate or something.
Ex: http://vart.institute/
Something where somebody can scribble lines and as the lines "age" they grow/bleed would be neat. Maybe something that changes colors as you draw. This could also teach structure and algorithms a bit as you have to model the drawing as an abstract concept instead of just pixels. OR the pixels could be the model and change algorithmicly so that as you draw the colors of existing pixels rotate or something.