There is a free preschool and kindergarten curriculum at http://preschool.earlyknowledgeforkids.org. The curriculum is laid out in sections and days, so you just go section to section and day by day. It has text with links to videos, games, coloring pages and worksheets. The curriculum covers science and social studies. The curriculum is still in progress but there is probably enough right now to last a couple of months. “Only parts of the curriculum are available at this time. The complete curriculum should be finished by the summer of 2012. New sections will be added regularly.”
You can also download free educational magazines in PDF format from http://www.earlyknowledgeforkids.org/ that are aimed at elementary age children.
If you are looking for knowledge building sites, I can only think of a couple at the moment. Brainpopjr.com is a really good website. But it isn’t free. It has a lot of really good educational videos. They have some free videos that you can check out. Gudli.com is another good site. Unfortunately, the electronic sounding voice can sometimes be a bit hard to understand. But it is free and does a really good job teaching various concepts.
Thank you for sharing! Karma to you!