I. remedial classes run by schools and teachers. One of them is the normal extra-curricular tutoring organized by the school, that is, the extra-curricular teaching time increased by the school in order to catch up with the teaching progress, which is openly organized by the school to supplement knowledge or strengthen practice for the exam, which is an expedient measure under the education system of exam-oriented education in China today. The other is that teachers think it is necessary for students to have extra-curricular tutoring, usually at the teacher's home, with group or individual tutoring.

Second, remedial classes run by some training institutions in society. These training institutions are divided into two types. First of all, it has its own teaching venue, management system and teachers, just like a primary school. Secondly, the society specially organizes directional cram schools for students who can't digest their knowledge at school, and they are taught by in-service or retired teachers. The content is basically outline review and a lot of intensive exercises.

Third, undergraduate tutors. This is a common form of extracurricular tutoring at present. Generally, parents, acquaintances, intermediaries and newspaper advertisements are used to find college students who meet the needs. After contact, meeting, communication, trial teaching and other procedures, the two sides reached an extracurricular tutoring agreement.