There is no where safe for your child to be online. That sounds extreme, but the simple fact of the matter is that child sex offenders are highly motivated, and sometimes, very skilled. They can go to any website and make a way of contacting children for the purposes of having sex with them or exchanging images with them, or exploiting them in any way. Far better, I think, for a parent to prepare a child to be approached by a child sex offender than to say, "You shall go anywhere but here on the internet. Here is safe, but here is not."