One word about teaching littluns code. Motivation. In my generation of geeks computers were new and interesting, and the motive was self generated. Today computers are so commonplace kids have a nonchalent disinterest.

But there is a foolproof way to engage them. Give them ownership of something. Not in a materialistic way, like their own computer, but in a virtual way, like their own home directory or website. Kids are naturally selfish, in a good way, so when they hear me talk about 'my home directory' the first thing I start hearing is "When can I have MY home directory?". Well, "right away" I say and create a user account. So now they want to add things, a custom login screen, a guestbook for their friends to visit, and so on. With these motivational hooks you have a reason and a context to teach.
Andy