Don't tell them how to circumnavigate it, eager teachers with pen and paper writing this down as we speak :-P
The only problem is that this will stop the laptop logging on away from the network at all. I think the OP wants the laptop to work fine away from the network for a month, and then insist on being returned to base so to speak.
Disabling profile caching could also be "fooled". As long as the user doesn't log out or shutdown (i.e. keeps placing the laptop into standby or hibernate), it will not stop it being used away from the network.