Are you looking for ideas for homeschooling them in these subjects or to suppliment what they are learning in school?

At this point it's to supplement grade school & pre-k. I'd be interested in any homeschooling knowledge though.

You might check out Bill Nye, the Science Guy's website. http://www.billnye.com/for-kids-teachers/home-demos/ Quite a few different experiments in several different areas of science. The Family Fun magazine website also has a lot of ideas. Intro | Activities-Games: Weird Science Experiments | Science Craft Projects for Kids | FamilyFun

Also check your library. I know ours has quite a large section in the children's department with books for teachers and homeschoolers.

Check out beestar. It offers online math, reading, social and science programs, full of all real life world problems, challenging stuff to help kids thinking. Pretty cool. DD has been using the free math. It helps a lot.
Lisa