1, the ratio of top students and poor students in each class is the same. This classification refers to the results of the last exam, from high to low. The first one goes to Class A, the second one to Class B, the third one to Class C, the fourth one to Class A, five or six students not to Class BC, and so on.
2. The ratio of top students and poor students in each class is different. This method is also a reference score. From high score to low score, the top 50 students are in Class A, 50 students are in Class B of 100 students, and 100 students are in Class C of 150 students.