Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
The best collection of Linux educational software for all ages that I know of is the openSUSE-Edu Li-f-e (Linux for Education) Live DVD.
There's a wide variety of "edutainment" software on this DVD for kids 12 years old and up. For the younger children, six years old and up, there are four packages designed to teach programming and one of the best collections of games for younger children. There are also games for adults.
Finally, there are a number of packages on this DVD for building school system servers and networks.