If you haven’t read it, I highly recommend the book Made to Stick: Why Some Ideas Survive and Others Die. This extraordinary book, written by brothers Chip and Dan Heath, poses a question that is critical for teachers everywhere: Why do we remember some ideas and stories, but not others? What makes an idea “sticky?”
The book ranges from urban legends to cognitive psychology; from successful ad campaigns to unforgettable classroom lessons. It’s fantastic reading for anyone who wants to become a better teacher or communicator.
In one chapter, the authors describe how new ideas are understood and stored more effectively when tethered to existing concepts or images. To illustrate with my own example: Imagine you were trying to describe the winter sport of curling to someone who had never seen it. You could begin by a detailed description of the icy court, the dimensions, and the objective – and fifteen minutes later your audience still wouldn’t understand the gist of it. Or, you could begin by saying “It’s like shuffleboard on ice.” With three words – shuffleboard on ice - your audience already has some concept of the layout and the general objective of the game.
As chemistry teachers, our job is to help students understand and remember a complex subject. How do we make it easier? In my own teaching and writing, I regularly use analogies, metaphors, and images that tie concepts to things they already understand. Of course, many teachers do this. But in the spirit of sharing good ideas, here are a few of my favorites, top-ten style:
10. Oxygen atoms come in packs of two, like peanut butter cups. (I extend this to the other diatomic elements as well.)
9. A barometer is like a straw. Why does the mercury rise up into a barometer? Why does liquid travel up the straw into your mouth?
8. Intermolecular forces are like the light from the sun, moon, and stars. The stars are always in the sky, but their light is negligible compared to the light of the moon or the brilliant light of the sun. Similarly, London dispersion forces are always present – but negligible compared to dipole-dipole forces or hydrogen bonds.
7. Activation energy is like the startup costs for a business. You may have a business idea that could make a lot of money (or lose a lot of money). But unless you have enough money to start the business, you’ll never know.
6. The plum pudding model. Okay – obviously this one isn’t mine – but think about it for a moment. Which was more important in the development of modern atomic theory – the plum pudding model or Millikan’s oil drop experiment? Which one do students remember? Even though the oil drop experiment was far more important, students remember the plum pudding model. Why? Because it’s simple, and it connects with something they can picture.
5. Your first date, or your first breakup. In my classes, I describe an exquisitely awkward moment from my middle school years in the 1980s, as I tried to ask a girl out at a skating rink. She could skate, I couldn’t. Thirty years later, it’s comedy gold. And it helps students see that the transition point – when you make or break bonds – is always higher energy than the moments before or after.
4. Heisenberg and the fan. When an electric fan is turned off, we know exactly where the blades are located. But if the fan is turned on, the blades move so quickly that we no longer know exactly where they are – we just know they are moving in an area that occupies a circle. Don’t stick your finger in the circle. In the same way, we never describe the exact location of electrons – Heisenberg’s uncertainty principle says this is impossible. Rather, we describe them by the shape they occupy. [Note – this crude analogy can help students begin to think about quantum mechanics, but of course it doesn’t address the wave nature of matter. A disclaimer may be appropriate.]
3. Single and double displacement reactions on the dancefloor. In a single displacement, one couple is dancing when a single person cuts in. In a double displacement, there are two pairs of dancers, and the dancers switch partners.
2. Enantiomers and diastereomers are like siblings and cousins. I begin by drawing the four possible stereoisomers for a molecule with two chiral centers. We label each center R and S, and usually label the pairs of enantiomers. Then I describe my kids, and compare them to my nephew and niece. We discuss the family relationships – siblings and cousins - then I go back to the stereoisomers to complete the analogy. The result looks something like this:
1. Limiting reagents in the kitchen. Before we dive into limiting reagents, leftovers, and the ICE method, I like to pose a question like this: "Suppose that you are making sandwiches following this recipe. You have 10 slices of bread and 40 slices of cheese. How many sandwiches can you make? What will you have left over?"
2 pieces of bread + 1 slice cheese → 1 sandwich
Most students can get this without a single lesson on stoichiometry. And if you can get students to tether stoichiometry to what they already know, the ideas become much, much easier. In my classes, we usually begin by working stoichiometry equations (complete with unit conversions) on sandwich problems. It works well.
I hope this list has spurred some ideas for you. And if you’re willing to share in a comment or email, I’d love to hear some of your favorites, as well.