You gotta take care of it right before hand! Or with your hand, hwvr you want to word it.
But yeah, the attention thing woulda prob been a problem. I mean you get to take frequent breaks because everybody knows standing or sitting completely still in one spot is actually kina difficult, there're lots of tricks to it. But they aren't long breaks, just for water so it isn't a mentally stimulating job. And if you crack too many jokes during it the students will ask for you back but the teacher will be reluctant