My school got a program called 'securus' (I think thats it) which auto blocks new links if then if its fishy it'll block it
Also you know when your teacher might block the internet? (ours does anyway) all you have to do is download 'opera' then you can go on the websites which are unblocked still.
Theres a few more ways to. But yeahh...Thats the best (easy)