Subject, that is, the meaning of category and grade, because since the Han Dynasty, scholars have determined the second grade through examination subjects. So in the old society, learning from teachers was also called entering a certain subject, and all the students enrolled in that year were in the same subject. A subject that is admitted or introduced to a drama team is called joining the league, or it can be called joining the league.

At that time, the performance unit was not called a troupe, but a troupe. The earliest training class was run by a troupe, such as the Sizhentang training class run by Sanqing Class led by Cheng Changgeng, the originator of Beijing Opera. Cheng Xiaoyu Keban, led by the famous Dan Tian Jiyun, whose stage name is "Nine Clouds", was an early supervised Keban. In the past, some opera actors were apprentices who learned from teachers, belonging to individual families or private schools. The troupe is mainly acting, and the class is mainly studying drama.

Regular classes are the organization of collective learning for later generations and the main form of cultivating opera talents. For example, Fu Liancheng's class is divided into eight divisions, namely, Xi Zi Division, Lian Zi Division, Fu Zi Division, New Word Division, Cross Division, Yuanzi Division, Yunzi Division and Qing Zi Division.

Because the imperial examination is the product of feudal society, the imperial examination also has a strong feudal color. For example, all classes worship Tang as their ancestors and worship him every day. Anyone who enters the class must make a written evidence, just like making a whoring contract, which not only means beating, scolding and corporal punishment, but also means serving three years in prison after work. Therefore, it was dubbed as a joke in the old society, and seven years in the class was called seven-year prison. However, due to strict teaching and management requirements, teachers have a certain sense of responsibility to preach and teach their ancestors, so they have also trained a large number of outstanding talents. Therefore, although the Chinese Opera School founded by Mr. Jiao Juyin in 1930 and various new opera schools established later have many improvements, such as abolishing corporal punishment and attaching importance to cultural education, they have also absorbed the advantages of oral instruction, teaching students in accordance with their aptitude, strict teaching and paying attention to practice in the past, which has brought forth a large number of opera talents.