[Zenka]

In the Netherlands you learn the traffic rules (at school) when you're 10/11 years old. There is a little exam even. It's normal children start cycling unattended from that point. However, children have been cycling attended since... when they are big enough to operate a bike that goes fast enough to do so (so say, from 5 years old.) Ergo they probably already know, in practice, how to operate safely in traffic.

When my parents caught me cycling home unattended during the longer school lunch breaks, and I confessed I've been doing that for most of the school year, they were like: "oh. Guess you know how to do that safely then. Carry on." I think I was 9 at that point. (It was a very safe route, which is common for Dutch home-primary school situations.)