Linda Dong, a friend of mine in the design department at CMU, has been working on this series of photos and videos demonstrating basic scientific concepts. What sets them apart from the rest is the attention to detail in her work: it's clean, simple, and usually on a plain white background. She even got some time on the school's scanning electron microscope to get images of a bug's eye and some pollen. I like the photos like this one representing potential energy:
Although they may not perfectly convey the concepts to people who aren't familiar with them already, these could probably be shown in a classroom setting and get the point across with a little explanation. These are more conversation starters than full descriptions, but they certainly made me look!