I might be stating the obvious, but I'd focus on what they can build, not the theory of it. Treat code like legos. With code, they could make toys for themselve

I might be stating the obvious, but I'd focus on what they can build, not the theory of it. Treat code like legos. With code, they could make toys for themselves, or to play with other kids. I haven't messed around with Scratch myself, but I know there are tons of robotics programming kits, and I think Lego allows you to program robots as well. That's how I'd approach it if I had kids.