At school, everyone forever wants to tell you what to do. Parents and school staff members are insisting on what you must think, which students you should and can't be friends with, what you ought to wear, and even what you ought to eat. It's a long list. You'd swear you're in prison. You would expect that while coercing you to go there and all that stuff, they would at least permit you to visit any web sites you'd like when you are stuck there. Alas, that is not the case. The internet is censored, and a good deal of web sites are blocked. Luckily, there are a few ways to unblock web sites, and it's a lot more easy than convincing your parents to homeschool you.
An unblocker is a kind of gateway that sit between the computer you're on and the site you want to go to. The unblocker visits the site instead of you, accesses the page, and sends it off to you. So the site you want to be on never sees your IP. So in effect you are surfing websites in an indirect manner. School firewalls think you are just accessing the unblocker, not the site you actually want.
An alternative method of unblocking Facebook at school is to set up your own unblocker site. This is harder than just using an unblocker but better in the long run because you're in control. Explaining how to do this is not in this guide, but if you search for "How to make your own proxy" you should find help. You can also earn money from letting people use it through advertising.
Other ways to unblock Facebook include by using sites that translate pages, for example Google Translate or Babelfish. You can also try using Google's cache copy of the site. Unfortunately, you probably won't be able to to login using these methods, so it's still best to use unblockers for Facebook, though these tips are good for most websites.