How to get on facebook at school?

If the school's computers are connected to their own proxy server that screens out all but pre-approved sites, how will that work?

It's just an idea, but on our school computers, where we have the security program iPrism and St. Bernard running at all times, we have to use a username that isn't restricted to student apps, programs, and websites, where you would be able to free roam on Google, and click any sites that would pop up that don't have any keywords that apply to being blocked, such as Game, Pornography, or Social Networking. Once you are onto the free proxy, however, the proxy has no internet security, so you can browse freely, and it will not save browsing history, cache, or cookies.