You may use following proxy , but you should consider the risk of using these proxies. You may get punish by your administrator if they know you using proxy at your school.
Ok , check fresh proxies below :
http://treeproxy.info
http://netzones.tk
http://foxfamily.tk
http://fastforward-proxy.tk
http://www.provpnaccess.info/
If you find above proxy are usefully , please share this post with your friend in school