Hootsuite allows you to manage your class social networks (Twitter & Facebook) from a single place. It also allows for scheduling of posts, which is tremendously helpful.
Hootsuite Overview Video
Here is more info about Hootsuite.
Article referenced about teens leaving Facebook: Here
All of this assumes you already have a Facebook and/or Twitter page for you class. If you don't, you really should have at least one. Hootsuite makes it easy to maintain both.
