The only advice I can give is to share my story.

I started my son at five with MIT's Scratch [1] followed up by Lego Mindstorms [2].

I then created a text adventure engine [3] that could run adventures written in a very simple Lua based DSL so he could make a simple text game [4]. Mom helped with spelling and grammar and I suggested a puzzle but he wrote the adventure himself.

Then I transitioned him to Lua on the iPad with Codea [5] and he (with a little help from me) made a game called StarFighter [6].

I choose Lua because it is a great intro language. Very simple with minimalistic syntax, few concepts, few primitives, few keywords, dynamically-typed / garbage collected, variable arity, no real gotchas, good tool support, great speed, the ability to access a key in a hash either using bracket or dotted notation, and one of the best programming books for any language (PiL).

But it also scales well; closures, first-class / true anonymous functions, metatables / metamethods, nice simple API for talking between script and C, tail-call optimization, coroutines, short circuiting operators.

And, the path from Lua to JavaScript is very straightforward. In fact I'd say that mastery of Lua would make you a mid-level JS programmer right out of the box...

The next step was JavaScript and ImpactJS [7]. I got him two books [8][9] and he loved them.

He is now doing HTML/CSS/JS and is in the middle of a fantastic book called Pro Javascript [10]. Once he is done with that book I am going to consider him on his own...

But just to give you an idea; he is 11 now and I am learning Scala for work. He's been watching videos with me and I paused it and ask questions and then I asked him where he thinks the presenter is going to go. He ran to his Ubuntu desktop and apt-get'ed Scala and cranked up a REPL session and showed me; he was correct!

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[1]: http://scratch.mit.edu/

[2]: http://mindstorms.lego.com/en-us/default.aspx

[3]: https://github.com/shawndumas/adventure.lua

[4]: https://github.com/shawndumas/adventure.lua/blob/master/theT...

[5]: http://twolivesleft.com/Codea/

[6]: https://gist.github.com/shawndumas/2762088

[7]: http://impactjs.com/

[8]: http://www.amazon.com/HTML5-Game-Development-ImpactJS-Cielen...

[9]: http://www.amazon.com/Building-HTML5-Games-ImpactJS-Introduc...

[10]: http://www.amazon.com/Professional-JavaScript-Developers-Wro...

I had rhino book but things got better when I read

http://www.amazon.com/Professional-JavaScript-Developers-Wro...