Demonstrating carbon dating with a plastic bottle

摘要

I was struggling to explain the concept of carbon dating to a year 10 group (ages 14–15) the other day, trying to think of a way to demonstrate it visually. I had vague recollections of baths of water with taps running and the plug out, but couldn’t quickly lay my hands on either a text reference or a bath. Spying a tray of empty plastic drink bottles that I had been saving for year 7 (ages 11–12) to make Cartesian divers with, I punched half a dozen small holes through the bottom of one (this can be done with a drawing pin or compass—see figure 1) and clamped the bottle in a clamp stand, with the bottle held vertically over a sink.