He is currently taking courses in school which are introductions to computers and programming. He is familiar with programming concepts from playing around with Scratch for many years. He also likes the idea of tinkering with robot like devices, even though there is little he has available to do so right now.
When I'm doing stuff with my Arduino and Raspberry Pi boards, he always develops an interest, but doesn't quite "get it" when I try to explain the details of what I'm doing with them. Maybe I'm explaining it wrong, or maybe he needs to learn it a different way, perhaps with a collection of hardware add-ons and project documentation which I normally don't use myself.
I would like to encourage the interest he develops, without initially overwhelming him with too many details. Either that, or he is a lot like me when I was growing up, and needs to do a little discovery on his own using these microprocessor based systems, which could lead to a more positive self esteem and appreciation for learning.
What I'm thinking of doing is finding something which merges robotics and computer programming. My first thought is Lego Mindstorms, but I don't know if/how powerful that system can become. I'm hoping to find something that can start off easy, but at the same time, the major investment in components doesn't go to waste because it can be outgrown too quickly.
I've checked on Arduino and Propeller based robot kits, but unless someone else can provide details on their personal experience with them, I think they may have a discouragingly steep learning curve to get started.
Any information will be useful. Are there relatively unknown, but useful kits out there. Is a "piecemeal kit" a better choice, with certain book purchases and a collection of individual components ordered from SparkFun, Jameco, etc? Are Lego Mindstorms a powerful and really good value kit for the money?