Continuous Everywhere but Differentiable Nowhere

This is too good not to use in the classroom… mwa hahahaha.  (Found via Digg: here)
A simplistic explanation (which is all I wanted) is here:
Your brain can make your hand write a 6 in the normal direction no problem at all, and it can circle your foot in a clockwise direction, no problem at all [...]

arXiv.org was originally designed to be a repository for pre-prints of physics articles, but it has since been expanded to other disciplines. I recently discovered that even though most of the math pre-prints are out of my league, there is one category of math articles that I have a good chance of understand: math history.
So [...]

Today I had yet another idea I had for a classroom that isn’t my own. It’s a bit of a long-winded post, so just look after the jump if the subject line intrigues you.