Anyone rarely does anything just for its sake. There's always some ultimate goals. As a become adult, programming became means of getting money and helping with business. When I was a kid, programming enabled me to make games and sandboxes that weren't otherwise available. I did some great things too.. but I never wanted to program "just for the sake of it". I wanted the results of that programming. Even if that meant a little fun sandbox game made by me.
It's not just computers, this is true for everything. Everyone does something for a reason. For me, programming was a way to create the games and sandboxes I dreamed of and enjoyed. I never really even finished anything, but I had my mind going around the AI and the general gameplay mechanics. Especially when I was waiting for bus or doing something other boring stuff. But, I was never really fascinated about computers or programming *per se*. I was interested at what those techniques could give me.
So rather than trying to educate programming, computer history or other boring stuff, try to tell what fun stuff you can do, or whatever he would be interested at. Everything else will come later, and the kids will either pick it up themselves or ask, if they want to.