Kids should have gum in school because fidget spinners are too distracting, and slime gets everywhere. When someone chews gum, it's a motor function, and it helps them concentrate on their work and it helps them focus, as well. I don't see why kids shouldn't have gum in school, because it's a good thing to keep kids engaged, and when they're done, they can just throw it away.
I'm sure we've all heard about the dangers of gum and how it can effect you. If gum is swallowed it can effect your blood flow, and that could result in death. Schools restrict gum to simply make it more safe for children. After all, school is supposed to be a safe and responsible environment and if something could have an effect of putting a child to death then it is just reasonable to restrict that thing from school.