Teacher education is not bad. I took a remedial class there before, and my grades improved, but it was not obvious. If you attend remedial classes, the effect will be better, but I think remedial classes are not very affordable and too expensive for students. This is my experience after finishing the remedial class. Some students in the remedial class have not improved their grades. You should find some suitable learning methods and find a fundamental one yourself.

After I went to cram school, my grades were not very good in my class. Later, a good classmate recommended me a learning blog, Li's Sina blog. Bloggers are the top candidates in the college entrance examination. His learning methods and problem-solving skills are very practical. I didn't get good grades in the past, and my grades in the cram school didn't improve obviously. Later, I saw a good learning method in his blog and my usual efforts. Now my grades are among the top in my class. You can use them after school.