The students raised their voices on her several times, as if trying to argue, which I found quite rude. If I were in the shoes of a teacher, I would probably warn the student that he will not talk to me in this way. However, the teacher does not say anything about it and thus shows the student that she can "try" further.
If I were in the shoes of a teacher, I would probably warn the student that he will not talk to me in this way.