In my kids' schools they always have those "earn a right" chips. Help the teacher file papers, you get to spend study hall playing board games instead of having to do homework. Help the teacher put the chairs on the desks at the end of the day, you get to watch "A Christmas Carol" instead of just having to read it and do a paper on it. Help the teacher erase the chalkboards, you get to skip that night's homework assignment. That stuff is normal.
Help the teacher file papers so you can go to the bathroom when you need to? Never saw it and hope I never do.