I was in a fifth grade classroom just before the holidays and saw a boy put a hand sanitize bottle on his desk with a timer taped to it. I asked him to explain and he said that if they want to go to the bathroom they pick one of the two bottles on the shelf (see second picture), set the timer for three minutes, and go to the bathroom. They have to make it back before the three minutes is up, use the hand sanitizer, turn off the alarm and put it back on the shelf.
The teacher said that the three minute alarm is her indication that someone might be playing or taking too long in the bathroom.
Clearly all the kids knew the bathroom procedure. There are two bottles for the boys and two for the girls. Apparently the boys lost one of the bottles before the break and they can only go out one at a time.
I thought this was a clever way to manage bathroom procedures so I thought I would share.