Yeah, I've read it, it's a good book.
Kids are... I don't know how to say it... not very smart (depending on the age of course).
I'm not a coach much less a coach for kids, but I'd just think something concrete like simple tactic puzzles would be best to start with.
I would be inclined to agree that the Stean is not likely to be a good choice for a kid. One can see a sample at https://store.doverpublications.com/0486424200.html .
Thinking about each move systematically is too complicated and takes all the fun out of the game. Kids like hacking and attacking the enemy. They need to discover the need to play defense too when they get tired of being beat up themselves.