My child attends a school that bans phones during school hours. It's easy to administer: every kid puts their phone in a phone locker as soon as they enter the school, and every kid retrieves it after the last class. The rare kid who defies the policy is easy to spot, and punished with temporary confiscation. The kids have lost nothing from this policy. They can still communicate with school friends using all the old fashioned methods that 20th century kids used. They still have access to computers, calculators, and cameras in classes where those tools are useful. The kids that I've talked to are happy with the school policy - they see it as fair, and appreciate that they're able to pay attention in school more easily without the distraction of phones.