And just a few decades later…

Two lemon batteries, connected in series, can (just barely) power a red LED.
Two lemon batteries, connected in series, can (just barely) power a red LED.

Making a lemon battery was one of the sciencey activities I encountered frequently while leafing through children’s science-experiments-you-can-do-at-home and “rainy day” activity books when I was a young’un and wanted to try but couldn’t.

As this article explains, a single lemon isn’t going to light an LED, but two will, by the skin of their nonexistent teeth, suffice.