The reason is that you are not confident enough at ordinary times. You are afraid to do the problem because you don't have enough confidence in yourself and feel that you can't do it well. Your heart is full of panic, so that you are "nervous even in class" Of course, this will greatly affect your learning efficiency, and your grades will naturally drop greatly.

To change this phenomenon, I think we should start from the following aspects:

First of all, you should have confidence in yourself. Build up confidence in yourself. You tell yourself that you can do this math problem well and you can learn math well.

Secondly, in class, you should actively cooperate with the teacher and even stand up to answer questions, which is worthy of your courage. I know it takes courage, but as long as you can take this step, it proves that you have courage. I believe you can overcome stage fright through more training.

Third, learning math is not a day's work. Do more exercises at ordinary times. Only by doing it yourself can you improve your math scores.

Finally, you should also build up your self-confidence in peacetime and communicate with your classmates more. Your ability and self-confidence will also make great progress in unconscious communication.

In view of your situation, the author briefly describes it here, hoping it will be useful to you and good luck!