I’m in Catherine Hildebrandt’s (@KKleinNYC) 6th grade math classes today talking about interior/exterior angles and showing the kids how to use Snap! to draw polygons.
I found a good lesson guide here:
http://scratched.media.mit.edu/resources/math-explorations-guides
Snap is basically Scratch running in a web browser rather than as an autonomous application on your computer. Snap runs really well on the iPad too, since it entails dragging programmable blocks into place in a browser window.
Michael Tempel of The Logo Foundation recently had an article published in CSTA about teaching programming to kids using a Blocks Programming interface.