Teaching with Documents - Lesson plans from the National Archives covering various periods of American history which use reproducible copies of primary documents.
History by Era - Overviews of various eras in American history with essays and primary documents related to the era from the Gilder Lehrman Institute of American History.
Historical Thinking Matters - Teacher resources to teach the importance of historical perspective. Four cases are used as examples.
TeachingHistory.org - Site put together by the National History Education Clearinghouse. Designed to help K-12 history teachers access resources and materials to improve U.S. history education by bringing history content, reliable resources, teaching strategies, and current research together in one website.