They say that he is not allowed at school or school activities. He has not been able to go to school for 2 weeks. Every Friday during lent our school won't serve meat because the Christians can't eat it, but we get a choice of a salad or yogurt instead of the main meal. If a teacher yells at you, whether you did something that deserves yelling at or not, you are not breaking any laws if you yell back.
All societies have social rules.
In our country we eat with forks and spoons, which is a social rule. In addition, schools, companies and organizations often have written conduct rules that are designed to promote good relationships and preserve order. If you yell back at a teacher, you're likely to be violating the school's rule against yelling at teachers. This could result in disciplinary action against you - a written warning, detention or worse. So you should think hard before you yell back to a teacher or adult in authority.