I love, love, LOVE Unsplash and subscribe for their updates so I get beautiful pictures in my inbox now and then. I will be adding some of these others. Thanks! Oh, I do use MorgueFile, but they're not the best composed pictures. Free, though, if you need something basic.
Comprehensive list on more than just CBE, including personalized learning, equity, students with special needs. I wish I had the time (and copies of all the books!) to get through all of this.