I lay awake for three hours, my thoughts turning and returning to teaching. I needed an analogy for radioactive decay, something that would get across both the randomness of what happens to an individual atom and the macro effects associated with a sample made up of a myriad of particles.
Ideas came and went. Did my son have any of these spring-and-sucker popping toys? One, if any. At around six o'clock, I hit on a possibility. When shopping I will sometimes slip a novelty food item into my basket, expecting it to appeal to my kids.
Occasionally they will request a new treat they expect to like. More often than not the idea is a bummer and only a fraction of the product is ever used. Are there any parents of young children out there who do not have a jar of peanut butter with one (and only one) scoop taken out? And we've got microwave popcorn.
It would not be quite fair to claim that my two didn't like microwave popcorn. They liked the noise, for a start, and the way the bag "grew" in the oven. They liked everything about it except eating it. For months, the two unused sachets in the three-pack hid behind some cereal boxes.
Don't ask me where the idea to use the grains with a little oil heated by Bunsen came from. It may not even be original. Whatever, it seemed to work. The class could not predict which grain would pop first, though they were probably more appreciative of the mess it made of my classroom.
Like most analogies, it had its weaknesses. We emphasise that radioactive emission needs no stimulation. It can't be triggered by heat. As with popcorn, radioactivity decays with time, but popcorn activity first rises to a peak and then falls. And genuine radioactivity experiments don't fill the entire lower floor of the school with a burnt-toast fog.
I love analogies and can come across all philosophical at times, describing my subject as "the big metaphor". (You don't really think physics has the real answers yet, do you? Seriously?) Next time I'm on the Internet I must try to find a physics analogy-sharing site. Maybe I'll find out a new way to explain a difficult concept, or mess up the classroom again.
And maybe, just maybe, I'll find a use for a jar of peanut butter with only one scoop used.
Gregor Steele welcomes suggestions on what to do with his peanut butter on firstname.lastname@example.org.