The first category refers to traditional formal education, such as classroom teaching in schools. In the first class, students learn knowledge and skills mainly through textbooks and teaching materials. The second classroom refers to various educational activities outside school education. In the second class, students can learn in various ways. The books used in the first class and the second class are different. The books used in the first class are textbooks and teaching materials, and the books used in the second class are all kinds of books.