I personally started by learning basic when I was about 9 or 10 years old...thing that got me interested was an open source game I used to play a lot. I accidentally stumbled onto the knowledge that changing the voodoo magic text at the beginning before launching the game (it was written in QBasic i think) managed to change things around in the game itself. If they like games, that could be a good way to start? It gives early rewards, as they're modifying something that already exists. From there I started getting ideas of things I wanted to make myself...and just experimenting here and there.
