I struggle with students wanting to constantly leave the classroom to use the bathroom. These bathroom passes have saved my instruction time!
Each student keeps up with their own pass (I laminate them), and must have it to leave the room. They get 5 passes. Each number left un-punched equates to an amount of extra credit points. For middle & high school students, this motivates them to stay in the room.
It seems juvenile, but I used this for high school seniors and the results have been incredible.