The following is a way to add to the strength of your filter:
Using your filter's block list, you can block common search engines (like Google and Bing). In this manner, the user won't be able to browse around the net, possibly getting into trouble. They will only be able to access sites if they know the domain name.
Go to the 'list' tab on your FILTER page and add the following popular search engines to your 'block list':
If you want to have access to other products that Google offers, add the related URL's to your 'allow list':
For Google Drive: