I love this blog post from teacher Krissy Venosdale. She makes the point that we, as teachers, must take the time to learn about and follow copyright law ourselves. We must obtain permission and correctly cite those lesson plans and images. Why? It's simple. The images don't belong to us, and we shouldn't pretend they do by not citing or getting permission. We must also teach (through modeling) our students to do the same.
Librarian, Ryan Ingersoll, on his blog Dripping Cup, argues that teachers should be modeling correct and ethical use of media/images in presentations and papers, rather than simply telling our students they can use anything they like under the "Fair Use" copyright category. After all, they will not be students forever, and their online activity isn't limited to teacher assignments. He also discusses the Creative Commons Zero license.
Unsplash photos are simply stunning, particularly the nature themes. The site is searchable by "collections," with headings like "repetition," "still life," "urban jungle," "workspace," and "black and white."