I am sending this bc I know this subject has come up before, not endorsing the concept or product.
For schools using AVG, this is included with the renewal cost.
AVG Content Filtering with patented V-routing technology is fast, flexible and highly accurate. Fully integrated with end-point security, our very thin client architecture keeps mobile and remote office workers productive wherever they are.
Simple and free to set up, AVG Content Filtering is the fast, flexible and highly accurate way to help your customers boost productivity.
No proxy required
Secondary local passwords
Email and text alerts
Automatic site blocking
Provide a second line of defence