This Guy Can Draw Circles Around You (And Me)

Found at Baekdal.com, where the author expresses some amount of whiteboard-skills envy.
The video shows Alex Overwijk, head of Glebe Collegiate high school’s math department (more trivia: Alanis Morrisette went there) drawing what appears to be a perfect circle.
This is something I do in my spare time. I draw freehand circles and then I found [...]

Hard Math

I found this photo at joe-ks.com. The title there is “Mennonite longhand math,” but can anybody identify the source or context? Can anybody work out the equation on the board?

I’ve convinced my friend Will, who teaches math and physics, to pose for a shot like this, but that means we’ll have find and fill a huge chalkboard…and he’ll have to grow his beard back.