The resources listed below are just a few of the places to find copyright-free images online. Wherever you look for images, remember to look for the license terms of a particular image or image site. For example, here’s Unsplash.com’s license page.
Remember to provide attribution wherever possible, and cite the external resources you’re using in your course. Modeling your field’s citation format right in your course materials can help your students experience the kind of citation habits you want them to develop.
Morguefile. A free image exchange for designers and teachers. Particularly good for stock photo-like images. Be advised: this site will also display search results from photo sites that charge money.
Unsplash. Beautiful photographs made freely available for use without attribution. It’s nice to give attribution anyway, though.
Flickr Commons. Vintage images from scores of museums and cultural institutions, under one search box.
New Old Stock. Daily selections of vintage photos free of known copyright restrictions.