Origami Proof of the Pythagorean Theorem
About this video
You don't need numbers of fancy equations to prove the pythagoran theorem. As self-proclaimed mathemusician Vi Hart demonstrates, you can fold it.
As "mathematicians are rebels and never believe anything anyone tells them" the video is an invitation to test and prove the theorem for yourself.
All you need is a piece of paper, a pen and a finger on the pause button to keep up with the rapid-fire instructions.
(The timing of the video at exactly 3 minutes and 14 seconds is a nice touch).
Licence: Standard YouTube Licence