What does "write up the entire class" mean?
Native speaker’s answer
"Write up" means "report to someone in authority". Therefore, when he says "write up the entire class", he is saying that he is going to report the entire class to the principal or someone who has authority at the school because the students were not obeying him. Ex: I'm going to write you up because you've been treating me unfairly at work. I want our boss to know how you've been treating me.