Google has long allowed parents a SafeSearch filtering setting that keeps kids from using the search engine to find inappropriate sites like those with explicit sexual images or text.

The problem was that kids could easily change those settings.

Starting Wednesday, however, the company is allowing parents to lock those settings to make it harder (though not impossible) for kids to bypass the settings.

To change the settings, the parent will have to log into his or her Google account and enter a password. Once the settings have been changed, the Google search engine will change in appearance to indicate that it’s locked. The new page will have large balls in the upper right corner so that parents can see from across the room that their kids are on the safe search page.

The settings, which places a cookie on the machine, must be configured for each browser the child uses. If you set them only for Internet Explorer, for example, they won’t restrict access from Firefox, Chrome, or other browsers. Also, according to a Google representative, the child can get around the settings by using the private browsing feature that is now built into the latest versions of Firefox, Internet Explorer, and Chrome. So, while this will keep kids from accidentally using Google for inappropriate searches, it will not deter tech-savvy kids who are determined to bypass the filters.

As I’ve said in other posts, filters are never a foolproof way to keep “tweens” and teenagers from inappropriate content. There are always ways to get around them, including using a different machine or mobile phone. Filters are effective for keeping young children from stumbling onto disturbing Web sites and they can be a deterrent to somewhat older kids who might have a momentary or casual interest in looking at material that their parents wish to block.

With all filters and controls, it’s important for parents to think about how you use them to help teach your child to exercise self-control and critical thinking so that, eventually, they can safely use the Web without filters or adult supervision. Also, for very young children, say 5 and under, its remains a good idea to be with the child while he or she is online. Tools like Google’s SafeSearch are helpful, but they are no substitute for close parental supervision, especially with young children.

Listen to Larry’s interview about Google SafeSearch with Google’s Scott Rubin