Doesn't seem like a big deal. RFID is not the same as GPS. There is an RFID chip in your passport too. All it'll do is tell them if you walked through a doorway...or rather if your ID card did. If they were surgically implanting them, that'd be another story. How is that different from a security guard with a notepad writing down what classes you go to?
No duh RFID isn't the same as GPS...if it was GPS there'd be no issue. GPS would be pointless for a school. Utilizing RFID is an issue however. This tech can do things from monitor your heart beats, to give out your name, via transmitting radio waves. If you feel comfortable having your child wear technology with such capabilities...to each his own I suppose, but that is a massive difference than a human with pen and paper.