When I was in second grade a parent who was a nurse came to school to teach my class about some health concepts. We spent a lot of time on proper hand-washing and germs. One of the things she had us do was rub our palms together so that the dirt and such became visible as little black spots. She said, “look at all those germs and microorganisms!”

I came home and repeated this experiment for my father, who then asked me, “if they are microorganisms, why can we see them?” I puzzled over this question for a long time, trying to determine the amazing procedure by which microscopic specks can grow large enough to be visible to the human eye.

Eventually I realized that the nurse had lied to me, and I found this highly disturbing.