On rainy days when I was a little girl, my dear mom, no doubt at the end of her patience with the busy and inquisitive child that I was, would sometimes allow me access to her button box. She was a talented and frugal seamstress, and she kept a dazzling stash of buttons, most harvested from discarded garments, in a fancy fruitcake tin. I loved to sit on the floor and sort the buttons into stacks by shape and color. Maybe it’s a genetic trait. A favorite aunt, a notoriously demanding nursing instructor, once told me that her ideal job would be sorting oranges.
Sorting is a skill that can help you succeed in the game of school. Once you start to figure out what goes with what, memorizing facts and writing papers gets a lot easier. Establishing how to sort things has made many scientists’ reputations…just ask Linnaeus. Sadly, some students’ childhoods must have lacked a button box, because they struggle with sorting tasks.
It doesn’t help that we apply intimidating labels, like “dichotomous keys,” to tasks that are basically just sorting, and simple sorting at that. For example, identifying an unknown bacteria with a dichotomous key boils down to plain old sorting. It just looks scary when depicted like this:
What’s a teacher to do? I like to lead students from what they know to what they don’t by taking small steps. Many of them are familiar with the game “Guess Who?,” so I dragged ours from the depths of the family game closet. Two willing students played a round that lasted less than a minute, identifying the culprit after only five yes/no questions.
Then I showed them a silly example from mental_floss magazine, including this one:
Next, they worked in pairs to quickly complete a nuts-and-bolts sorting task using a dichotomous key I found on the internet:
Finally, they were ready to see how a multi-test identification for bacteria is basically just a fancy, colorful dichotomous key, a bit like having a group of tiny elves in a tube answering a series of yes/no questions for you while you sleep. What could be more fun?
If you have anything that needs sorting, give me a call…happy to help.