If the school is creating an environment where disruption is tolerated, that’s the problem. And as a parent should absolutely council your children to not be disruptive in class. But “6 7” isn’t the problem here.
As it should! Just know that people between your age and their age see the common through-line here, and it might not be as serious as it feels. I’ll become blind to it as well in a while haha, sadly comes with becoming more wise.
Personal anecdata: 69 showing up in any math class was comedy gold in early 2010s highscool. The class was interrupted for impromptu 1 word stand up.