My student Thomas is really very naughty, for example I would ask him to answer a question, he knows the answer but he purposely tells me the wrong answer, trying to be funny. He likes to draw during my Chinese lesson and not pay attention. Today I shouted at him, I said "Behave yourself, understand?" He got a shock and says Yes I understand. I need to be more strict and firm with him because he is really very mischievous, cannot be too lenient with him.