At school, you're incessantly being told what to do. Parents and school staff are insisting on what you should think, which students you ought to and shouldn't be friends with, what you ought to wear, and even what you ought to eat. It's a long list. It's like prison, apart from the fact that you did nothing wrong. You would think that after pressuring you to endure and all these things, they'd at least let you visit whichever web sites you like while you are visiting there. Alas, that isn't the case. The internets are censored, and lots websites are blocked. As luck would have it, there are a couple of ways of getting around that at least, and it's a lot easier than getting your parents to homeschool you.
An unblocker is like a gateway that sit between your computer and the site you want to go to. The unblocker goes to the site on your behalf, downloads the page, and sends it on to you. So the site you want to access never sees your IP. So in effect you are visiting websites indirectly. School firewalls think you are just accessing the unblocker, not the destination site.
Another method to unblock Facebook at school is to set up your own unblocker tool. This is more complicated than using someone else's unblocker but it's a lot nicer to have because you're in control. Explaining how to do this is not in this guide, if you do a search for "How to make your own proxy" you will find info. You can even make money from your unblocker if you put ads on it.
Other ways to get on Facebook are to use translator sites, such as Google Translate or Babelfish. You can also try using Google's cache copy of the site. Unfortunately, you can't to log in that way, so you're better off using unblockers for Facebook, though these tips work well for many other sites.