Inspirograph

This (or, even better, a physical Spirograph, together with a document camera) is spectacular for teaching mathematics.

In my calculus class, we wrote down parametric equations defining the curves you get.

In my abstract algebra and number theory classes, I got the students to figure out the rule predicting how many loops the figure will have.

Full source available here: https://github.com/nfriend/inspirograph

as someone who really enjoyed playing with the plastic-and-ink version as a child, this is awesome!

Excellent job! I had a spirograph as a kid and this brought back a lot of memories.

I don't know what I'm doing here but I like it and keep doing it.

Is there any way to drag the inner gear using iOS?