Analogies and Acronyms

Explaining something successfully is greatly helped by using an appropriate analogy. That’s because it’s much easier to learn something new by scaffolding it to previous knowledge. Without any scaffold, if you’re trying to learn a bunch of new things simultaneously, your working memory gets overwhelmed. Prior knowledge of the vocabulary is crucial. If you don’t understand the words, you’ll get bogged down very quickly. For example, an introduction to Atomic Theory could have been written as “Uncleftish Beholding”. As a chemist, I can see what’s going on but it’s still a struggle. For a non-chemist, it reads like utter gobbledygook.

 

I first learned science in high school in a language that was not English. Scientific language did not use everyday terms and I was totally lost. I couldn’t even understand the definitions. Things seem a little easier in English because words such as “atomic” and “theory” have everyday meanings. But there are problems. In a scientific context, a word might have a very precise meaning. While in everyday use, its meaning might differ. For example, the scientific definition of theory (which means very well supported by numerous facts) carries connotations almost opposite to how the word theory (which might infer something that has little basis in reality).

 

We can’t see atoms or molecules. But we can picture them with analogies such as balls connected by springs. The balls have different sizes (as atoms do) and different colors to represent the element (which isn’t true, but the colors are extremely helpful for visualization). We represent these atoms by symbols: H, O, Na, Cl. With these symbols we construct chemical “formulae” such as H₂O, HCl, NaOH, and NaCl. For the trained chemist, each of these formulae trigger a wealth of associations.

 

For example, by seeing the formula NaCl, I simultaneously picture table salt (white and granular). But in my mind’s eye I also see a crystal lattice consisting of a face-centered-cube of larger chloride ions with sodium ions in the octahedral holes. My mind then jumps to the lattice energy, that can be calculated by a Madelung “sum” of Coulombic terms that represent the ionic bonds. (I’ve inadvertently introduced jargon that the non-chemist will find obtuse!) This then makes me think of the enthalpy of dissolution of NaCl in water, which is an endothermic reaction with a very small delta-H. Thus the dissolving of table salt in water is entropically-driven at room temperature. NaCl probably has a K_sp > 1. I picture ions being pulled out of the lattice by polar water molecules and I recognize that this is an electrolyte. The solution has pH 7 because HCl and NaOH are strong acids and bases that react to form NaCl. And I could go on. The point here is that seeing the symbols NaCl immediately generates a wealth of connection in my minds.

 

A beginning student in chemistry won’t be making those rich connections. The student might still be thinking: What is Na and where is it on the periodic table? In my mind, there are analogies galore. I’m picturing not just colored balls in some arrangement, but I see mathematical equations, fields of force, energy diagrams, and more. And in class, when I discuss the structure, formation and dissolution of NaCl, I have analogies to bridge the gap to help students gain the type of expert understanding that I have. I want them to be able to evoke the rich set of connections that helps them understand what chemistry is all about (really)! As they make more connections and “solidify” their understanding (ah, another apt analogy!), building on this scaffold (another analogy!) helps them learn more and learn deeper. Analogies are everywhere. You can’t think without them. You can’t talk without them.

 

I’m teaching myself biochemistry. I’m not an expert. Yet. One of the things I’ve been wading through is the alphabet soup of acronyms. An acronym is a stand-in, that once you understand it, allows you to reduce your cognitive load by using it as a scaffold to learn more complex things. One acronym we’re familiar with is DNA. An acronym “hides” details, and by doing so, allows you to use it as a conceptual piece to build up a web of information. (Why a web? Why not a jungle?) As a chemist, I’m still hung up on the detailed chemical structure, but when one gets to regulation and control, you want to think of these macromolecules as blobs with acronym names: ATP, AcCoA, NADH. I’ve even started using three-letter acronyms for the molecules in the Krebs cycle: ACE, OXA, CIT, CAC, ISC, AKG, SUC, MAL, FUM.

 

I’ve come to appreciate that acronyms are not just shorthand so I don’t have to say a mouthful for a name, but once I know what they mean (chemically), they release my mental resources to build on the scaffold. This is one of the humps that students need to get over. It’s why they should memorize the three-letter and one-letter codes for amino acids, and have a good idea of what the side chain looks like and its properties. Without internalizing this, every time they look at an enzyme active site or read about single-site mutation studies, they don’t really “get” what’s going on because they’re still stuck in trying to determine what Ser-His-Glu is before they can understand its role as a catalytic triad in AChE (acetylcholinesterase).

 

Analogies and Acronyms: We need them to learn new and complex things! As teachers we should utilize them in powerful ways to help our students make the journey from novice to expert.