If a teacher taught a student and the student did not lean,what would the teacher do?

You must diversify methods and means of explanation

It is important to understand the psychology of the students. Depending on situations different techniques and methods should be applied. One should not stick to traditional approaches only. Student’s interaction, question and answer session, inviting students to contribute their own ideas/experience and peer work could be helpful in resolving difficult situations. 

the teacher can repeat his information to student and use another ways to make him understand like films or computer 'powerpoint ... " or stories