I'm with you on this.
I can understand controlling the use of phones during class because it's disrespectful for the teachers work, but a complete ban is just dumb and seems like virtue signalling.
If this is a problem for you as a parent, you have the choice of not buying your kid the phone in the first place, or not letting him take it to school.
I thinks that any rule or law that takes away from the parents the responsibility of educating a child is probably not good for the kid.
Also specially in the US with all the school shootings, banning kids from having phones that allow them to call for help seems like a really bad idea.
Also specially in the US with all the school shootings, banning kids from having phones that allow them to call for help seems like a really bad idea.