Teachers know this special face-changing skill because they have special needs in this profession. The communication between teachers and students is not the kind of communication with a particularly large gap in status, but teachers should have a basic position in the hearts of students, that is to say, they should have the most basic awe of teachers and should not be seen by students. This teacher is not afraid at all. If he doesn't listen to the teacher, he can't carry out this teaching work. So he must be as serious as possible when he is in contact with students.
Teachers usually have their own behaviors. Because in a high school, class representatives have more contact with teachers. Teachers are very amiable, and then they are willing to help our classmates in life. However, when they are in class, they are in a serious state in the classroom, and they will not often joke with you, because in such a teaching link as the classroom, it is necessary to maintain a fixed role setting, that is, the teacher is the teacher and the student.
The profession of teacher is very special, because it affects the growth of many people anyway. Maybe the teaching staff is not as noble as you think. Not all teachers can be selfless and dedicated to the public. After all, that requirement is too high, but most teachers can do their duty, impart their knowledge to students, help students grow up, help students master more knowledge and achieve better results. This basic requirement of professionalism has been met.