The smart schools block the ip and not the domain name nae . For example: Myspace.com. If you try mail.myspace.com the filter it set for domain names and not sub domains and still detects myspace.com.
My middle school used a system where there where four rj 45 plugs in the wall. The top right was the internet blocked, the bottom right was the network only and the top left was for teachers which only blocked porn but allowed myspace and the small things.. So we 'dropped our pens' and changed the plugs. It was funny to see the teachers have there comers lag when a class was in the computer room on the teachers network =P