pornography not being blocked

I am testing my son's computer just to see what comes through the blocking software and am so disappointed to find that when I type in "breast" and click "images" the screen fills with images of not just medical-type websites but lots of raunchy, sexy, nude-breasted photos come through.  Then I try "pornography" and screen after screen of images and pornographic websites are available.  I am a teacher with my own school - issued computer running the K-9 software and it is doing a much better job of blocking all of this inappropriate content.  My son's computer shows that Norton Family is running and I have check that pornography is blocked in the family rules for his devices.  I don't know if something isn't working right in the Norton program or if the Norton Family software is not effective.  I have assumed for months that it was working and am so dis heartened to see that it may have been ineffectual.  I've spent over 30 minutes looking at the forum for suggestions and haven't found any.  I would love some guidance.