The Canada Science and Techhonology Museum website contains several photo essays.  The topics include: Canada at War, Origins of wilderness tourism in Canada, and Railways in Canada.
http://www.imagescn.technomuses.ca/photoessays.cfm

From the CBC World Photo Gallery - A Pictorial look at how we affect our envrionment.  An excellent photo essay with a message.
http://www.cbc.ca/photogallery/world/3310/

Canadian War Museum - Photographs as History lesson plan
http://www.warmuseum.ca/cwm/exhibitions/guerre/pdf/4-a-3-all_e.pdf