Selecting reasonable teaching content is a prerequisite for preparing lessons. The selection of teaching content should be determined based on factors such as the characteristics of knowledge, the intention of writing teaching materials, the time required to complete teaching tasks, and the actual situation of students. . How to reasonably choose the teaching content of a lesson? The first thing is to choose according to the layout of the teaching materials. Usually we divide the knowledge of an exercise into several small paragraphs, and each small paragraph is the teaching content of one lesson. The current mathematics teaching materials are arranged in this way. When preparing lessons, teachers only need to take a look at the new teaching content and corresponding exercises in the teaching materials. By writing, you can determine the teaching content of a lesson. The second is to choose based on the difficulty of knowledge. Generally speaking, for knowledge that is relatively simple and easy for students to accept and understand, you can choose more content; for knowledge that is difficult for students to understand and grasp, since it takes more time in teaching, you should choose less content. When choosing the teaching content of a lesson, the specific situation should be treated in a specific manner, and the teaching tasks can be successfully completed in a lesson and the knowledge taught is conducive to students' understanding and mastery.