Encyclopedia Smithsonian: Art to Zoology
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The Smithsonian has linked to a broad range of materials here, including history, science, art and culture. A good first source for material or information. Some topics include lesson plans, and all are fully referenced. The entries are aimed at adults, but most topics are appropriate for children. It is all available for free.
My favorites so far: Zoology
American History Timeline (not exhaustive, but worth some time)
and Geology.
Also, check out the Smithsonian Collections Search Center -- lots of art, scientific documents prepared by Smithsonian employees, and primary historical sources. This tool seems designed for scholarly research, not idle browsing, but could be ideal for a homeschool student with a specific interest.
