That’s the policy at most schools. Actually enforcing that in the face of a classroom of kids who don’t respect the rule? That’s a much bigger problem. They’re a lot more clever at sneaking them out than you would think. Moreover, if the phones are just feet from them, their presence is never out of mind. They’re a constant distraction even in a bag. Phone apps are literally designed to be addictive. Imagine if we had a rule that said “crack pipes are fine in your bag. As long as you don’t take them out and smoke in class, you’re fine.” Even if we lived in a world where crack somehow was legal for minors to have, how effective to you think that rule could be enforced?