How should I preview? Junior students have less literacy and poor study habits, so we can guide them to preview. For the first-year students, I started by teaching them to read: the first step is to learn to read the catalogue and understand its function, so as to fully understand the contents of the book and quickly find what I want to read. The second step is to learn to read the information window. First look at what the information window describes, then look for mathematical information, put forward mathematical problems and think about solutions. For example, when previewing the information window 1 of "Addition and subtraction of numbers within 100" (the second volume of senior one), I asked students to look at what their friends are doing in the information window first, and then find out which words are connected together to form a math problem. Finally, think about how to solve this mathematical problem with a formula. For some practical and operational knowledge, they can prepare teaching AIDS in advance and experience the process to preview. For example, when I teach classification and comparison in grade one, I arrange for students to go to the supermarket with their parents before class, so that they can pay attention to how the goods in the mall are placed. Let them clean up their schoolbags and wardrobes with their mothers, and let them feel the importance of classification. The teaching content appears with the "situation" around students, which increases the reality and interest of mathematics teaching, makes students realize that there is mathematics knowledge everywhere in their lives, mobilizes their enthusiasm for learning mathematics and can stimulate their interest in learning mathematics.

With the gradual enhancement of junior students' learning ability, they sometimes no longer need teachers to lead the preview, but often simply understand the preview as reading a math textbook. It is difficult for them to go deep into the textbook, think independently and actively explore new knowledge. Some students also think that after finishing the tutorial or the exercises after the book, it will be over. They regard preview as a boring task, which will lead to a decline in their interest in learning mathematics over time. In this case, I often guide the preview methods in stages and purposefully, put forward clear preview requirements and steps for students, and teach them specific preview methods. For example, take "what to do-how to do it-why to do it-what you don't understand" as the step to preview. And the preview tasks assigned to them must be moderate in difficulty, interesting and operable. It can also be designed to preview the outline.