Mimi Ito is a cultural anthropologist at UC Irvine. Her brief YouTube explanation of the ways tweens and teens use social media would be great to share during professional development or a parent night.
The key takeaway for me was the distinction between friendship driven versus interest driven ways kids use social media. Recognizing that kids use social media the way some of us used our Princess phones years ago is important. Those friendship driven activities may seem like huge time wasters, but kids are learning how to negotiate social behaviors.
Helping parents and teachers recognize that kids can also use social media to learn (what Ito calls the "messing around" and "geeking out" interest driven activities) is tremendously important. Making remix videos, recording podcasts are just two examples of interest driven learning that kids do online. I think it's important to recognize that informal, interest driven learning in the classroom.
Ito discusses a lot more in this brief video, but I suggest you watch it and take notes! If you want to delve further, MIT Press has a free download of Hanging Out, Messing Around and Geeking Out available on their website.