American Photography: A Century of Images
This site, designed as a companion to the PBS film, is quite useful in its own right. Among other themes, the site explores the role of photography in American history, beginning with the role of photography as a relative newcomer to art.
In addition, the site examines the ways in which photography has impacted warfare, politics, and advertising. Moreover, the site raises important questions about whether photographs portray a subjective reality and whether photographers influence viewers' perceptions through cropping or digital manipulation. An Image Lab allows visitors to explore the ways that camera perspective and cropping can change the meaning of a photograph. Visitors can use the tool to manipulate stock photographs and view the results.
A Teacher's Guide provides five lesson plans, asking students to decide whether censorship is a worthwhile practice and to consider ethical issues related to altering photographs.
Not a particularly deep collection of images, this site's strength is the way it teaches how to evaluate and understand photographs, especially historical photographs.