Mathematics in the first semester of Grade 8 is different from that in Book 1. In the education system, the first grade is the first grade of middle school, which is equivalent to the first half of the seventh grade. Usually, mathematics courses will gradually increase the difficulty and depth between different grades and introduce new concepts, principles and skills. Therefore, the mathematics course in the first semester will continue to expand knowledge and skills on the basis of the first volume of mathematics in the seventh grade. The mathematics in the first volume of the eighth grade will continue to expand knowledge and skills on the basis of the first semester. Therefore, the mathematics content of the first semester of junior high school and the first volume of the eighth grade is different as a whole.