Always check a website's use policy. Just because something is on the Internet, doesn't mean it's copyright free or that you can use it, copy it, download, etc.
Search Engines:
Yahoo
Bing
Picsearch
DuckDuckgo
J. Paul Getty Museum Open Content (Only the Open Content Images may be used for free - only search that part of the website.) Many historical photographs, drawings and paintings as well as copies of old manuscripts.
http://openclipart.org/browse Lots of copyright free images. The few that aren't are clearly marked. Kid friendly.
http://www.easystockphotos.com/index.html Many different categories of copyright free images for teachers and students.
http://pics.tech4learning.com/ All free, designed for teachers and kids
http://www.copyrightfreephotos.com/ All free pics
http://photo2.si.edu/ The Smithsonian Institution - Low resolution images may be downloaded for free. Better quality images have a small fee.
http://classroomclipart.com/ Free clipart for everyone. Covers wide range of topics and includes both photos and illustrations.
Not all images on the sites listed below are free or available for web use. Read the use rules for the site as well as the description for each image carefully before downloading.
http://www.freefoto.com/index.jsp
http://photography.nationalgeographic.com/photography/wallpapers/?source=NavPhoWall
http://freerangestock.com/index.php
http://www.publicdomainpictures.net/
New York Public Library
http://www.nypl.org/research/collections/digital-collections/public-domain
The British Library
https://www.flickr.com/photos/britishlibrary/
Wikimedia Commons
https://commons.wikimedia.org/wiki/Main_Page
Creative Commons
https://search.creativecommons.org
Free Images
Pixabay
FONTS