I really don't have anything to say about this article except my agreement that using something that is interactive, not passive, can help in teaching various concepts. Demos in class are fine for a quick demonstration of a concept, but people won't really learn anything new until they are able to play with it themselves. I've used the an interactive illustration for cs123 and it was very helpful, so I know that they do some good. Hopefully other classes can find good uses for these types of projects, and the students will be able to benefit.