Serendipity can often lead to new ways of teaching physics. Let me tell you about an incident that happened about 40 years ago in my introductory physics laboratory.
That week we were studying the formation of images by converging lenses. Following the format of this experiment that probably dates back to the beginning of the 20th century, the lab had a series of optical benches set up, each with a light source, a screen, and a lens holder between the two of them. The light sources were the traditional lamp houses, fronted with an opaque screen with a cross and an arrow cut into it. The images were starkly black and white, and the students took data to calculate the focal length of the lens using the familiar 1/f = 1/p + 1/q; after that they went outside with a meter stick and measured the focal...