There are three kinds of classroom review: reviewing the old knowledge related to it before speaking a new lesson, which is called preview; After class, teachers often do some exercises while the iron is hot, which is a preparatory review for digestion; At the end of a class, sort out, summarize and summarize what you have learned in this section, which is a combing review for the purpose of absorption.

The purpose of after-class review is to eliminate forgetting and strengthen memory. No matter whether the teacher leaves homework or not, he should compare the class notes with the teaching materials before doing his homework.

Unit review refers to the review after completing a chapter or a group of contents, mainly to compare similarities and differences, find internal relations, and filter and accumulate.