I would start off with Logo. http://logo.twentygototen.org/ http://logo.twentygototen.org/ While it is very simplistic, it is also super-easy to get started a

I would start off with Logo. http://logo.twentygototen.org/ http://logo.twentygototen.org/ While it is very simplistic, it is also super-easy to get started and create something visible on the screen (which I suppose is important for a child not to lose interest). You can convey a lot of very basic yet important concepts, and immediatelly visualize them (Iteration: draw an n-polygon or growing objects, Recursion: Snowflake like fractals, and so on). If your child catches on, you then can ease in into something more sophisticated.