As mentioned in a previous post, I have a Google+ account but do not use it. Google+ is a cleaner form of Facebook, free of the many games and apps that clutter Facebook. It used to also be free of teenagers pretty much. But now Google+ is opened up for anyone 13 and older, so our students could sign up for their own account too. Google+ is still dominated by the professional and adult world and teens are not flocking to the site right now, but if they do, Google+ does have several safety features built in for security. And they also have features teens may like (Google Hangouts and Video chats). Click on this blogpost from Educational Technology Guy to learn more.
Educational Technology Guy's post about Google+ Change to Allow all Teens to be Members