how to lock out proxy servers

This is probably the opposite of what most people ask about proxy servers, but... I have a kid who is homebound and so signed up for an on-line high school. He's using my laptop (Vista Premium) which logs onto our home wireless network using LinkSys. We blocked some programs using the control panel and parental controls when we found out he was goofing off when we weren't watching--going to Facebook and other sites. So he started using a proxy server to go around our blocks. So I got OpenDNS and used it to block proxy servers... only it doesn't block some... and there are thousands of them out there. Other then blocking the entire internet and only letting him on a few selected sites, I'm not sure what else I can do. That would be a pain, since he has to do a lot of research online and I'm not always home to put his required sites on the unblocked list. My wife is leery of doing anything with the computer... Any thoughts? Our local high school does a good job of blocking proxy servers but they have an expensive security program that requires a hefty monthly fee.. I need something free or cheap.
Keith

 

Discuss the problem with the High School.

They may be able to give him the privilege of connecting from your home and into their system and through their system's "expensive security program" to access internet sites that they approve of. Then you just have to block him from any site other than the high school.

Alan