I actually live in the school district that has created the issue. You can find the original printed notice here:
From the language used, they seem to believe that their policy is enforceable by law. However, the actual text of the law says nothing about compelling access to a personal social network profile. This leads me to believe that a degree of incompetence has invaded the district's administration. Shocking, right?
I don't expect it to happen, but nonetheless I am telling my kids that if any authority figure at school asks for access to any of their personal accounts, they should defer to me so I can pass the issue along to the lawyer.