Andrew Watts, a 19-year-old at the University of Texas, posted an interesting piece on Medium titled, A Teenager’s View on Social Media.
He breaks down the popularity of Facebook, Instagram, Twitter, SnapChat, Tumblr and YikYak in the “highly coveted” demographic of which he is a part.
Most interesting to me are his views on Facebook:

In short, many have nailed this on the head. It’s dead to us. Facebook is something we all got in middle school because it was cool but now is seen as an awkward family dinner party we can’t really leave.
This makes total sense. Mom, Dad and all your and all your aunts and uncles are on Facebook. LAME-O. But, wait:
Facebook is often used by us mainly for its group functionality. I know plenty of classmates who only go on Facebook to check the groups they are part of and then quickly log off.
And:
Messaging on Facebook is also extremely popular among our age group, mainly because they provide the means to talk to those people who you weren’t really comfortable with asking for their number but comfortable enough to send them a friend request.
So, despite being “dead” to the kids, they continue to use Facebook a lot. I’m willing to bet they use it potentially as much as other, more cool social networks like Instagram. What’s interesting is Andrew seems to define “using” a website/app as posting content to it. Simply “checking in” on it—like teens do on Facebook—doesn’t count. Server logs and analytics tools would beg to differ.
It also seems Facebook’s move to decouple messaging from the core Facebook product was a smart move. Facebook is perceived as a crazy, loud, public zoo (because it is), but Facebook Messenger is a discreet way to talk to someone.