I enjoy working with our team to develop on-line interactive education activities. We are in the final testing of whose goal is to teach about the balance of global water, land coverage, atmosphere and cloudiness required to create a "liveable planet". If you want to play with it and give us feedback - here is the link:

http://profhorn.meteor.wisc.edu/wxwise/climate/makeplanet.html
The goal is to make a habitable planet by adding enough water, atmosphere and clouds to reach a global average temperature of about 15°C (59°F). You can mix and match, add or remove.

* Drag (and drop) an item from the right side to the left to add that element
* Drag (and drop) from the left are back to the right to remove that element
* HINT You must put at least 3 clouds by the planet!!

There is a timer to see how fast you can make the planet livable.