The central link in the teaching process is to understand knowledge. This link includes making students perceive and understand the teaching materials, among which understanding the teaching materials and forming concepts are the central links in the teaching process. This link is the process of teachers answering questions for students, which needs bilateral activities of "teacher teaching" and "student learning" to complete. Teaching process refers to the change of the activity state and time flow of teachers and students jointly realizing teaching tasks. It includes two interdependent aspects: teaching and learning. The internal development motivation is the contradiction between the teaching tasks put forward by teachers and the needs and actual level of students to complete these tasks. China ancient educators put forward "learning, asking, thinking, distinguishing and doing" (the golden mean), which is the earliest summary of the learning process.