Teachers often don’t teach well in class. They always talk off-topic and brag, wasting a lot of time. Even in physics, they learn by themselves.

I have carefully read the questions and descriptions you raised. My views and suggestions are as follows:

First of all, the phenomenon you described is very common. Some teachers now, In class, he likes to talk about content that has nothing to do with the subject matter he teaches, and he also calls it euphemistically: activating the classroom atmosphere.

When you encounter such a teacher, it is useless to report him to the school on your own. Because his relaxed and lively teaching method is still liked by some or most of the students in your class. As long as you cannot reach an agreement, jointly submit a letter to the Academic Affairs Office and report the teacher. Then, the school's Academic Affairs Office will not accept reports from individual students or parents.

So, you can combine the tutorial books and study carefully. If you encounter something you don’t understand, ask the teacher questions after class. Improve your academic performance through your own efforts.

The above are my suggestions and are for reference only.

I hope my answer can help you and satisfy you.

Finally, I wish you a happy life and progress in your studies.