When profs erase what they’ve written on the board to make room for a next example, do they feel loss? It’s a bit like having a day’s worth of office work burned up before your eyes by a lighter-wielding devil, only on a smaller scale. What have you to show for yourself? Nothing, it’s all been erased…by myself no less. It of course depends on the mental manufacture of the prof concerned, but I’m sure some of them feel a part of themselves being killed as they reluctantly wipe away the marks they’ve made with dry erase.