Also has tips on internet research and more. Also links to other virtual libraries. Contains more than 500 categories linking to more than 17,000 sites.
Most sites note the appropriate grade level.
Normally, the answer itself is not supplied - just suggestions on how to find it. A handy collection of maps, dictionaries, biographies and other research tools. Contains 16,000 articles and more than 2,000 photos, illustrations, maps and charts. Nice collection of dictionaries, including a hypertext-linked Webster's. Try it out free for the first month.