Surely, your students are familiar with geology—and don’t call me Shirley. They know, at least, the basics: that, geologically speaking, the deeper down one digs, the older what one finds will be. This is, more or less, the Law of Superposition, a unifying geological theory and one that is of crucial importance in all fields of scientific dating. (That is, scientifically figuring out how old something is, not scientists dating each other.)
To give students (or whoever you’re demonstrating this for) a hands-on example of the Law of Superposition without the need for a shovel, break out the ol’ laundry basket!
Leave Out the Underpants
Obviously, you don’t want little kids digging through your dirty laundry, nor do you want to dig through theirs (unless you’ve got a modular cleanroom or something like that handy in which to safely handle that mess of bacteria and stank). So, the smart move is to bring in a bunch of clean laundry in a hamper. Fill that sucker to the brim for maximum learnings!
Don’t just toss in your trousers, socks, shirts, and what-have-you all willy-nilly, though. For the purposes of this Demo Science science demo, your laundry dump will have to be a little more deliberate. Arrange your threads in layers so that each layer has common characteristics. Layers can be arranged by similar colors, similar clothing type (a layer of just sweaters followed by a layer of only right socks, for example), brand name—however you want to do it, as long as there’s a recognizable theme across the board.
Gather your students around and have them take turns removing a single piece of clothing. Make sure they’re keeping an eye out for the potentially scientifically-important “characteristics” of their excavations, and appoint at least one kid (not Kevin) to take notes and record the class’s findings.
When they’ve reached the bottom, discuss their observations and the relevance of their findings—whatever those findings may be!
Superposition Science Studies
Much like deeper dirt is older than the layers of soil on top of it, the laundry at the bottom of your basket are “older” and were “worn” before the clothes on top. (Though, since it’s clean laundry, that’s not actually the case, but you know what we mean here.)
And, not unlike how you arranged the layers of your laundry, geological layers deposited during certain “similar” time periods usually have similar characteristics. This is used to determine the dates of events and learn about specific periods of geological history.