I respect the efforts the author put in to teach kids how to program. That being said, I really don't think HTML/Javascript is the right choice for kids. The web stack is even considered messy from professional web programers' perspective. My son will turn seven soon. I did some research on programming languages/kits for kids around that age. I finally settled down on Robomind, which is more or less of a modern varia…
Its so great that you are involving your son with robotics. Really awesome. You should definitely keep working on that. In fact, keep me updated on how you guys progress along. My email is in my profile.