University of Michigan
University of Michigan: Spy Letters of the American Revolution
A wonderful resource with letters, stories, people, and timelines of spies for the Loyalists and the Patriots during the American Revolution.
Other
Archives Pei: Heritage Fair Projects a Guide to Sources [Pdf]
A comprehensive resource for students and teachers for planning and researching a project for a heritage fair. While it is intended for Prince Edward Island residents, it offers excellent tips, web links and books for guidance.
Curated OER
History Matters: Making Sense of Documentary Photography
A great guide to making sense of documentary photography. Learn ways to distinguish between early and modern photos, where the photo was taken, and how the photo was presented.
US National Archives
Nara: History in the Raw
Site offers excellent reasons to approach history by using primary documents -- diaries, letters, drawings, and memoirs. Also gives teachers suggestions on where to find great sources.
Library of Congress
Loc: Does the Camera Ever Lie?
A presentation of how photographs were manipulated by photographers during the Civil War.