Many US schools require students to lock their phones into a pouch during the school day.

This seems to be a good thing, as far as I can tell from the article, but it doesn't do the whole job. It ought to block the phone's radio reception and transmission, so that the phone can't track the students' movements in school. It should also block sound; otherwise any phone can keep listening to the whole class, if its software has been remotely modified to do that.