In some countries to some people? Yes. It is illegal in Thailand to call the king fat.

In the context of schools most places verbal insults are not crimes. But what I’m saying is that the shouldn’t be treated as a criminal matter. That’s why it’s good to not have police in schools. Because if a kid refuses to do what a teacher says it’s not a crime, but refusing a police officer in the US is failure to follow a lawful order which is a criminal offence.