Know when not to revise. The content in the textbook requires students to know the whole half hour and how many minutes, and it also involves the calculation of the transition between simple moments, which is difficult for children to accept and understand. However, in the mathematics of the first grade of primary school, the new PEP only knows clocks and watches, and only requires students to know the whole hour, which is easy for children to accept happily. So what you are talking about is not two courses, but the knowledge difference between the two versions of the textbook and the change of students' goals.