This book is the work of a famous mathematics educator, covering the contents required by the current education syllabus, and is the teaching material of Mr. Sun's three-round experimental class. This book is based on the analysis and grasp of basic knowledge and the guidance of methods and ideas. Each chapter consists of two parts: study guide and examples. After refining the concept, the laws, methods and thinking rules of the periphery of the concept are extended. It is pointed out in the book that in order to learn mathematics well, we must look at problems from a systematic perspective, strive for multiple solutions to one problem, multiple solutions to one problem (a conclusion), multiple problems to one problem (good at summarizing), and be good at thinking about problems from a "dynamic" perspective (optimistic about the scenery), which is of great help to open students' mathematical wisdom, master scientific learning methods and thinking rules, and improve learning efficiency. This book can be used as a tutorial or self-study textbook for middle school teachers and students.