While I am teaching 4th grade, this is what worked for me. I have a token economy system in which the students earn classroom money. I noticed that many of my students were going to the bathroom a LARGE amount of times
and that it was contagious. I started taking classroom breaks in the morning and afternoon and if they need to go at a time beyond that, they have to pay me some classroom money. This stopped the problem RIGHT away.
Perhaps for you, with 7-8 grades, you could offer them the chance to earn "Bonus Bucks" by asking a trivia question about the day's work at the end of class. These could
be worth extra credit points on any assignment or test. Give them one or two passes for a designated amount of time. If they need to go beyond that, they would have to pay a bonus buck to go to the restroom.
