This is a topic that has been part of much discussion in educational circles over the last few years - balancing the access and restrictions to internet sites by educational institutions. This is a thorny issue and one that has not been resloved yet.
Clearly educational institutions want to encourage appropriate use of computers and so those who misuse the Internet access should be prevented. In addition there are sites that may cause problems from a technical perspective and so these too need to be restricted. The issue then becomes how useful are some of the websites for education and do any of these need to be unblocked. In discussions at conferences and online forums the debate continues with the IT/technical staff explaining the need to control access (for many good reasons) and the teaching staff and students pointing out the value of some blocked sites (again with valid justification).
Not an easy issue to resolve but one that will require communication between all parties!