Is it legal for teachers to read students' short messages privately?

Of course, this is illegal. Text messages, and letters. Usually letters are written, written on paper. Short messages are on mobile phones and belong to electronic information. The only difference is the place where it is written, and the essence is the same. It is illegal to read other people's letters without their consent. For the above situation, the teacher is not a law enforcer, and it is illegal to view other people's mobile phone messages without the approval of the relevant departments!