It's hard for me to say since I've never had kids before. I personally don't trust facebook at all, and if it wasn't for my writing on hubpages, then chances are i would delete my fb accounts permanently and never bother with that site again.
I do know there are ways you can block certain sites whenever you use the internet on public computers. like back when i was unemployed for a while, i know the work source center i went to help find another one allowed you to use computers there. heck, it even had internet access, but the only thing is it restricted you from going to social sites, or anything that wasn't work related like say job search sites, or your email like at yahoo, hotmail and etc.
Am I suggesting that schools should do this? Um...yes and no. I can see schools wanting to obviously block sites like porn sites, or something like that. But if we're talking about social sites like facebook, then that's a bit debatable.
On the one hand, i don't see it as a big deal as long as it doesn't interfere with the kids learning stuff. but at the same time, i can see how it might be counter productive. i do believe there should be a mandatory class in schools warning kids about the dangers of the internet though if you want me to be honest, but outside of that, you can't really shelter your kids from everything.