When I was in college, we found a pile of old blackboards behind a classroom building that was being renovated. Of course we had to rescue a couple of them and

When I was in college, we found a pile of old blackboards behind a classroom building that was being renovated. Of course we had to rescue a couple of them and put them in the common rooms in our dorm. Mostly they were filled with random graphitti, but we also often put up mathematical brainteasers and it was interesting to see people's attempts at solutions. They stayed there til the end of the semester, I was sad to find them gone upon returning next year.