Given the task definition and input, reply with output. In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.

Article: In the United States, headmasters and teachers discipline students in several ways. The teacher often writes to or calls the students' parents. Sometimes students have to stay at school for one hour. If a student behaves very badly, the headmaster can stop the student having classes. The student can't come to school for one, two or three days. Mr Lazares, the headmaster of a middle school in Ohio, did not like to do so. When he didn't let the students come to school, they were happy. "A three-day holiday!" they thought. One day, a boy was in Mr Lazares's office. The boy was not behaving well in class. Mr Lazares telephoned the boy's parents. "If you come to school with your son, I won't stop him having classes." He said. The boy's father came to school and went with his son to every class. Other students looked at the boy and his father. The boy was embarrassed . After that he behaved better. And, of course, other students behaved better, too. Now headmasters all over the USA are trying Mr Lazares's idea. They, too, think that students behave better when parents come to school.
Answer: Stops the student having classes for several days.
What does a headmaster usually do to the student if he behaves very badly?