The Anxious Generation: Hoe the Great rewiring of Childhood I Causing an Epidemic of Mental Illness by Jonathan Haidt warns of the harm done to children who live in a phone-based world with limited opportunity to play and connect with the real world. There is serious research to support banning phones in schools and keeping kids off of social media until they turn 16. This could well be the most important book I have summarized out of well over 200. Every principal, teacher, and parent needs to read it.