First, the key to learning mathematics well is to learn to preview, so that students can learn the content of the new lesson independently before the teacher gives a lecture, make a preliminary understanding, and make good knowledge preparation and psychological preparation for class. Learning to preview is a key step to adapt to high school study as soon as possible, and it is also the understanding and application of new knowledge by freshmen in high school to improve learning efficiency. The premise of learning to preview is to make it clear that learning to preview is the basic quality of modern freshmen. The significance of preview is to cultivate good study habits, learn to study consciously, master the methods of self-study, and lay the foundation for future study; Preview is helpful to understand the knowledge points, key points and difficulties of the new class, and can remove some obstacles for class; Preview is helpful to improve the effect of listening to lectures. When previewing incomprehensible or vague questions, it is easy for teachers to understand them when they explain them in class, so as to really achieve the purpose of previewing. The basic method of preview is "reading, remembering, writing and searching". "Reading" means reading the textbook carefully first, understanding the main idea of the textbook, and then reading it carefully and repeatedly according to the characteristics of the subject, such as mathematical concepts, laws and examples. "Marking" is to mark the theme, key points and difficulties, and to mark the key points, difficulties, laws and concepts of a class to help you remember when attending classes. "Writing" means writing your own opinions, experiences and explanations in the corresponding positions at the edge of the book to avoid forgetting. "Check" is the effect of self-examination and preview. It is best to close the book, think about what you have just read, what you can understand at first sight and what you can't understand vaguely, do after-school exercises and check the preview effect.