Why not just have the teachers make a phone call? You have wall phones in every classroom. There's zero need for the kids to have phones.

Yes, you can find niche scenarios where every kid having a phone may be useful, but we're already talking about very rare events. We're sacrificing our children's education for the sake of minute physical safety risks.

There are dozens of teachers, teacher's aids, and staff in a school. They can all have cell phones. You're just starting with the conclusion, "let's find reasons for kids to have phones," and working backward from there.