Khan Academy
Practice exercises and instructional videos for math, science, computing, history, art history, economics, and more, including K-14 and test preparation content.
Reviewed Websites
Library of Congress Digital Collections
Search the Library of Congress’s curated digital collection of primary source material, including maps, photographs, letters, and audio recordings
Science.gov
Search for scientific information from a variety of databases supported by 13 federal agencies, including NASA and the National Science Foundation