1. Record the examples explained by the classroom teacher and summarize each example. It is necessary to summarize the usage of a knowledge point in the example, the solution of such problems, and some special skills.

2. Record all kinds of formulas and deformation formulas. It is a formula or a regular conclusion in itself. Let's call it the second kind of formula or the second kind of theorem. For example, in the chapter of trigonometric function, you need to make clear the source and derivation process of each formula.

3. For the concept, it is necessary to record the key points, keywords and deeper understanding emphasized by the teacher.

4. For theorems, the conditions and usage of theorems should be recorded.