Recently I've been involved in numerous discussions about how to protect young kids from inappropriate material on the web. The first was prompted by a friend concerned about what appeared to be violent adult material sent to her young son by a friend. Not being an expert in the area I turned to Wendi Kamiya, Punahou's CTO, for advice. She explained Punahou's system, which uses various types of filtering including heuristics, white lists and black lists. Policies are adjusted on an ongoing basis and regular reviews are performed to determine if bad sites are getting through or educational sites are being blocked. Of course, they also do plenty of good old fashion manual monitoring. It sounds like they do an excellent job.
Obviously it isn't practical to implement a system like Punahou's on a home network, so the school recommends parents only allow computers to be connected in common areas. Computer use is permitted elsewhere so kids can, for example, program in their rooms, but they can only connect in common areas. This of course isn't a perfect solution because kids can jump on their neighbor's wireless network or use a smart phone. The iPhone and Nexus One have large, bright, high resolution screens and they are always connected. A friend of mine in Japan half-joked that an average Japanese teen has two or three IP addresses on their body at any time. Essentially, there isn't any way around manual monitoring. Based on my conversations with Wendi and other education IT specialists it sounds like the average parent who is not involved in IT will be surpassed by their kids in terms of technical sophistication around the age of 12. For some it will happen as young as 9 or 10.
Kids are increasingly technically sophisticated and motivated kids can usually find a way around any technical solution. I have friends with 10 year olds who are capable of setting up proxy servers. One of our friends has a 12 year old son who writes iPhone apps in Objective C without any assistance. Luckily his maturity seems to be in step with his technical aptitude, but anyone who thinks they can limit these kids access via technical means is kidding themselves.
I'm interested in hearing how those with kids in this age range deal with regulating web access.