I happened upon a charming origami proof of the Pythagorean theorem. It’s just one of many math videos made by the also-charming Vi Hart, who seems to have boundless energy for math and its more whimsical sides. For example, see her rant about why Pi is (still) Wrong, complete with pie.

Vi is the daughter of George Hart, a geometer I have long admired. George is now the chief of content at the Museum of Math, which is opening next year in New York City.

Links from all of these pages lead to all sorts of wonders. I would have put more of them in this post, but I couldn’t choose, and spent too much time looking at them myself...