Look no further, there's actually an entire learning platform/ OS designed for this very purpose: Sugar.
The OLPC (One Laptop Per Child) operating system called Sugar is now available to the general public and you can run it as a VM within all major operating systems such as Mac, Windows and Linux.
Download a copy at Sugar Labs.
One interesting activity included is called TurtleArt, a souped up 21st century version of Logo. Also has a kid friendly version of a Python IDE called Pippy. It actually teaches kids Python!
See TurtleArt and Pippy and the other activities found in Sugar.
Alan Kay was behind some of the novel concepts in Sugar OS which is actually a modern incarnation of his visionary DynaBook. Even as an adult (who's an engineer), I find it fun to play with.
And if you love Sugar as a VM, you can even buy the hardware and at the same time help a poor kid somewhere else in the world.
Engadget explains : OLPC XO Buy-One, Give-One program underway
As a bonus to us adults, Sugar is derived from Fedora. So it's a real and complete Linux based OS. Should be fun to hack. ;-)