I agree with zevi8. It’s impossible to shelter children from everything. And the likelihood of them accidentally stumbling upon some immoral site is slim to none. Websites with offensive material always have screens requiring the user to click a button certifying that he is over 18 and does not object to pornographic material before they show anything.
Feivel, just because children cannot operate cars does not mean that they are not in danger when they ride in them, even in booster seats. I currently live in Israel where the rate of car accidents is alarmingly high and injures a great number of children- just go look in Alyn Hospital, and you will see all the children who are mentally and physically handicapped from these accidents. Yet people still drive in Israel, and they still put their children in cars. The solution is not to stop driving, it is to drive less recklessly. So too, the solution here is not to block the Internet from children, but to find a working system of monitoring their usage of it.