|I really feel sorry that I can't give a great answer to you. |
The real answer ought to be that ISP's should be required by law to restrict access to the web to families. It would be a fairly simple matter to have a law to rate sites like any other public product and force ISP's to offer ratings levels.
Until public officials care about children the second best way is to have a firewall device that only you have access to. Some home routers have some firewall features and some time restrictions. Kids may not be able to bypass that.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.