> We should get together and just give each other such puzzles. Would be nice. > I suggest we work on a blackboard instead of on a whiteboard. I think they ar

> We should get together and just give each other such puzzles. Would be nice. > I suggest we work on a blackboard instead of on a whiteboard. I think they are nicer. Using blackboard and chalk is indeed nicer. The unpleasantness comes afterwards, when you have to wash the chalk off of your clothes.