I am very enthusiastic about this proof, which could readily be used in the third or fourth grade. I expect to use it at that level. The proof is both sound and intuitive: kids would be able not only to see that it works but also to have a good sense of why. Two questions:

#1: Any history? Is it ten years old or a thousand? At minimum, I'd like to know what I can call the proof (other than "Proof #9 at http://www.cut-the-knot.com/pythagoras";). Have you any leads on the discoverer, or at least the medieval abbey at which it was discovered?

#2: Are you aware of any educational supply company that produces a jigsaw-puzzle version of the proof? With such materials and a little guidance, kids could discover the theorem for themselves. Custom manufacture is of course a possibility, but it would be expensive. If there are copyright considerations, I would like to know about these as well.

Thanks in advance,

Peter Brown