I can remember the blackboard rubber being thrown across the class room!
This has reminded me of a jibe that was planned in my class at grammar school. Each pupil was to collect a piece of blackboard chalk and keep it handy.
One particular teacher used to throw his chalk at someone who was not paying attention, so it was decided to set him up (and I deny any involvement

).
I removed All but one piece of chalk was removed from the blackboard tray before the lesson started, and when the inevitable piece of chalk was thrown at a victim, the teacher had no more chalk and asked for the chalk to be given back

He had a good sense of humour, fortunately
