You need to be firmly aware of the legal boundary lines with any and all social media with students & FERPA...
"Two things to always keep in mind:
1. ...never reveal information about students that might indicate their grades, course enrollments, class schedules, and so on....
2. ...Any document or communication (digital or not) that is considered an educational record for purposes of FERPA is subject to the "inspect and review" privilege by the student.
If you play by these rules, you should be safe and in compliance."
"Is Your Use of Social Media FERPA Compliant?"
-Perry D.Drake
http://tinyurl.com/ferpacheat