Kollelboy, I am sure your intentions are pure, but I strongly believe you are mistaken. Kids waste money all the time, and they could not care less about it costing too much to use the intenet on the phone. Most of them have a cell plan that includes texting, anyway.
Kids use their phones to CHEAT during tests, by texting answers to each other (this has been demonstrated to be fact), and if you think that frum kids would never do that, then I have a lovely bridge I would be interested in selling you. There is absolutely no reason why kids should have cell phones available to them during school hours (recess or lunch period being the exception with which I would be comfortable). If they are NOT going to use them during class, then there is no reason for them to be on their person. If they would need them for an emergency, they could get their phones from the rebbie right away. Having to sumbit to random pocket checks, ensures that they have nothing they shouldn’t in their pockets, and that they do not have a SECOND phone stashed away after giving in the first one. Yeah, kids do that, too. The first phone was not even a usable one. It was a “beard.”