Math and numeral games for kindergarten through sixth grades. 

http://www.rainforestmaths.com/

Fun interactive games for young children that reinforce numbers, letters and using the mouse.

http://www.poissonrouge.com

Educational games created by the Australian Broadcasting Corporation to help younger children understand numbers.

http://www.abc.net.au/countusin/games

http://www.pestworldforkids.org/learninggames.html

How can zoos help save endangered species? By breeding them in captivity, in hopes of someday releasing animals back into their original habitats. This interactive places you in charge of a breeding program for endangered tigers. Choose from several breeding plans, then make the best matches to ensure tiger survival. Along the way, you'll learn about tiger genetics and the basic rules of inheritance.

http://www.minnesotazoo.org/education/games/matchmaker/index.html  

http://hubblesite.org/explore_astronomy/black_holes/modules.html

Google SketchUp is an easy-to-learn 3D modeling program that enables you to explore the world in 3D. With just a few simple tools, you can create 3D models of houses, sheds, decks, home additions, woodworking projects - even space ships. And once you've built your models, you can place them in Google Earth, post them to the 3D Warehouse, or print hard copies. Download a free version here:

http://sketchup.google.com/  

Take on the challenge facing bridge designers and design a bridge that can withstand a Maximum Seismic Event—then test your bridge to see how it fares! (Requires Flash)

http://www.newbaybridge.org/classroom/engineeringfor.html  

The Starfall learn-to-read website is offered free as a public service. We also provide writing journals and books at a very low cost that can be used with the website or separately. Teachers around the country are using Starfall materials as an inexpensive way to make the classroom more fun and to inspire a love of reading and writing.

http://www.starfall.com/

Games and public service announcements to help keep kids safe on and off line.

http://www.mcgruff.com