Why shouldn't i talk during class?

First, it is rude. Second, it won't help you if you don't learn. By talking you are telling the teacher that what you say is more important than what they are saying. You might miss important info and you won't know how to do your homework. It might also be on the test and you would miss the question. If you are doing a test the teacher would think that you were cheating and give you a 0. That is not fun