Note, I decided to solder the switch on the front of the board as the instructions say is an option; this way we can turn on the board as we play with it more easily!
Evil Mad Scientist's kits:
http://wiki.evilmadscientist.com/Octolively
The $90 Spark Fun Kit is also highly recommended.
Over the Christmas break we played with it with our 7 year old niece and 11 year old nephew.
The 7 year old had just enough motor control to place all the leads into the breadboard, whereas the 11 year old was programming combined exercises together -- sound + buttons, morse code, reaction game, ...
https://www.sparkfun.com/products/11576







