How do you say this? First of all, it depends on your own level or the low level of teachers. Suppose that if the teacher's level is low, then everyone or most people in the class think it is necessary to change teachers, and they can talk to the dean. But my personal opinion is that if he is going to fail you at the end of the year, there is no need to make such a fuss, just study by himself. The head teacher of a university used to teach some books. I studied accounting, and most of the knowledge was acquired by him.