This site offers education resources for educators and students on the topic of the U.S. Constitution. This site has games, videos, lesson plans, and more for free.
Choose a grade level then look around for information on how the U.S. government works.
This site offers teaching resources and self-paced courses on civic education in the United States. *Some courses and materials require purchase*
This site provides pro and con arguments to controversial topics in a straightforward, nonpartisan way.