[hocuspocus]

First, the idea of a school running checks on Facebook sounds pretty comical to me. Your schools are definitely over-funded if they have the time and resources for that. I went to a school that is the topic of several public groups on Facebook, including a satirical web-comic that was run by a student for many years.

But more importantly, do you realize nobody forces you to post or share anything? And even if you do, it's very easy to restrict permissions to a few selected circles. Your family members send friend requests? Fine, add them to the "restricted" list. A lot of people (me included) have stopped using the main newsfeed, and I notice that most of the picture sharing is done on Instagram nowadays, but it's still a convenient tool, especially when you have friends on every continent. And it's really not that hard to keep things private.