Use a proxy service to block adult content
If you ever turn off content filter on your browser, you'll be surprised how many innocuous searches can result in hits on pornographic material from URL that doesn't hint at their content. I don't have young children at home so I haven't used such software, however I use Proxy servers for different reasons and know that many also offer content filtering service. Once such reputable service that offer a free basic package for family is OpenDNS. Following is a link to their website for the free basic solution and a more comprehensive solution for under $20/year.
OpenDNS Parental Control Solution: