Here I would like to collect a list of software pieces that could be useful in teaching, or simply that are useful in transmitting knowledge to children.
I personally used some of these with my kids (currently aged 9 and 12) since the age of about 6.
I will be refining this entry over time, so the first edition will be necessarily not clean nor complete.
Kids like colors and paints.
Artrage by Ambient Design is a very interesting paint program.
It simulates well the brush with oil colors, on many different types of canvas. Also allows pastels, chalk colors, and many mixed techniques. Artrage basic edition is free and there is an even more powerful version with additional features and effects. Artrage is available for Windows and for Mac.
A number of websites exist with templates that can be used for fill painting on pc or to be printed on paper for real coloring action. Here is a website with a nice selection of cartoon characters.
Also the basic paint programs that come with the basic operating system can be a good start.
Windows paint is also useful for some quick sketch.
I like physics simulation software.
Phun by Emil Ernerfeldt is a great free software for building machinery and to test what happens. Phun is a simulation environment in which you can play with bidimensional objects.
Go search in youtube for many examples of exilirating "Ruby Goldberg" machines, like this
here is the phun commercial.
Crayon Physics by Petri Purho. This is somewhat simpler than phun. It is like a game and comes with a numers of levels to be played.
Rube Goldberg machines
this makes the kids go crazy.
look if you can find "the incredible machine". it is an old pc game, easily found in cd attached to game magazines.
Anim8tor by R. Steven Glanville
Pivot Stickfigure Animator by Peter Bone
Plastic Animation Paper :
just fun to see xiao xiao animations, in many places all over the net, for example here
Artoonix: a great software for animation. fun to use and to prepare .avi or flash files.
Stellarium: this is a wondeful "home planetarium" ideal to learn how to recognize night sky, constellations, stars and planets.
Celestia: this is more like a "space simulator" in which you can arrange a trip among the solar system planets, accelerate time, and change observation perspective. A lot of details are available. Also ultra detailed maps are availaple for many celestial bodies.
Google earth: earth, the moon, and even mars
Nasa World Wind: a sophisticated environment from which you can access meteorological and environmental data