how can i get facebook unblocked without teachers knowing.?

[Alex]

Odds are there is no way you'll be able to do that as suck blocks are rarely computer level and are more commonly on the firewall.

Unless you can access the firewall and can remove the facebook blockages...there is little you can do to bypass it.

Not to mention that if you were to bypass it and were caught, you could be in a lot of trouble as bypassing security is often more severe an infraction than just hanging out on facebook in the first place.