At my middle school, we also banned smartphones throughout the whole building. You were meant to either leave yours at home or put it in your locker when you got there. It's a lot easier to chat with people during the breaks when they're not face-down in their phone screen.

Who would have thought?

The "study" is that they asked teachers, "Hey, how's it been going?" and the teachers answered, "I feel like my students are paying attention more now."

How were they ever allowed?

I was in school from the transition from no mobiles at all to smart phones. If you got caught with one it was whipped off you.

Who better to poll than teachers for this type of study? They are the ones in the trenches and can gauge the results.