I had mind numbingly boring classes when I was in school. Why were they boring in the first place? Cuz the curriculum was stupid/the teachers weren’t that good. The solutions to both problems are by increasing the education budget.
I also had teachers who were so amazing that noone was distracted. My point is, kids don’t use phones in classes for absolutely no reason. Kids do that cuz the classes are shite. Fix the classes and the kids won’t use their phones.