@igelsQTs I think MIT Mathematicians refused to use anything else. They had 3 chalk boards that were on like an ellipse shaped track so they could have 2 stacked at once. There were like 4 of these systems in a classroom.

Mathematicians hate the white boards and I feel the pain. White boards lose the ability to erase overtime. Chalkboards just needed to be cleaned.

I've seen like 3 generations of the markers. The solvents used in the early generations were somewhat close to drug precursors lol. It's all rather impressive but it begs the question of why. Chalk can go back into the environment, the weird film pigment is probably not that good.