This question might be odd, but after watching one of Gilbert Strang's lectures I find I am jealous of his great, smoothly flowing chalk that never seems to get dulled down. Anyone know what it is, or a better replacement for the "crayola types"?
I had completely forgotten about this question and came across it again recently, so I decided to email Dr. Strang. To my surprise, he responded almost immediately. The chalk he used is called Railroad Chalk, and you can find it at many popular online retailers.