The bounden duty of a teacher is to teach and educate people. No matter how busy the main job is, it must be a student. No matter how bad the students are, they should teach seriously, otherwise it is dereliction of duty. If you can't even specialize in your own job, how can students study well in the future?

Don't try to make money by running extra-curricular cram schools. You should think more about how to teach in order to make students understand, how to make courses more attractive to students, and how to make students love learning more. ...