Traditionally, a "class hour" in school is 40~50 minutes (mostly 45 minutes). In social institutions (generally training institutions), a "class hour" is one to two hours.

In addition, the unit of measurement of education and training time related to "class hours" is "class hours". Class hours refer to the learning time calculated by class hours. It is generally believed that both non-adult education and full-time university education are 40-minute classes. Therefore, if 30 class hours of training tasks are needed, the effective training time is 30×40= 1200 minutes, 1200/60=20 hours.

The World Health Organization stipulates that a class lasts for 45 minutes, which depends on the degree of eye fatigue and the duration of cerebral cortex. The most effective memory duration of human cerebral cortex is 45 minutes. After this time, memory will decline and eyes will be tired. Take a break between two 45 minutes 10 minutes to relieve the fatigue of the brain and eyes, and then study for the next 45 minutes.

Nowadays, college courses are all academic progress in class hours.

The class hours of adult education are different according to the characteristics of the industry. For example, the class time of physical training is usually 30 minutes, while that of adult vocational education in Shanghai is 90 minutes, with a break of 15 minutes (smoking and going to the toilet). That is, from 9: 00 am to 10: 30 am, 10: 45 am to 12: 00 am.

The unit of measurement of education and training time related to "class hours" is "class hours". Class hours refer to the learning time calculated by class hours. It is generally believed that both non-adult education and full-time university education are 40-minute classes. Therefore, if 30 class hours of training tasks are needed, the effective training time is 30×40= 1200 minutes, 1200/60=20 hours.