Capture my kids search engine searches

I would like to somehow capture google searches my kids make. I use the web filter lite which does a pretty good job. I also use opendns as well as a second layer. As a preventive layer I would like to be able to capture words my kids are searching for on google or other search engines just to get an idea of behavior trends. Then if certain key terms are found I want to alert myself of the search. I know key loggers can do this but then I have to put them on all devices and admin all that. If I could capture that in untangle then I don't have to worry about each device or devices neighbor kids bring over. I would have a log I could parse and alert off. I assume this has been discussed but I couldn't find much in the forums.

Thanks,
Jared