I asked my students how they’d found the APC exam a few years ago and one student said:

“It was fine. Question 1 was Billy squared and Question 3 was an easy Charlie”.

What? Well, spoiler alert. The Benefit of Naming Equations is that it provides a framework for their cognitive architecture in the APC calculus world, AND it reduces cognitive load because they don’t have to re-remember which one we’re talking about every time. This matters. Because capacitor discharging is Billy and capacitor charging in Charlie. Lock gates are Billy, so is Newton’s law of cooling… it is SO cool. It is REALLY worth doing.
I wish I’d realised this 38 years ago.

It all started with Billy the Bullet.
Billy goes into jello/jelly with a retarding force of F = -kv. As bullets are wont to do. Hey ho. Here’s that derivation:

We got used to talking about Billy and Charlie. Often the first retrieval practice question was ‘Do Billy velocity and displacement’ or ‘do Charlie velocity’. Or ‘Billy squared’ where F = -kv² .

Then one day…
Carson (APC student): ‘Wait, what happened to A?’
Me: ‘What do you mean?’
Carson: ‘Billy… Charlie… what happened to the A person?
Me: ‘Aha!! Well, let’s work out what should have come first…’
The Class with one voice: ‘Banked curves’.

So at this point the naming convention became a point of discussion. Obviously they go in alphabetical order, but what else? Gender neutral was the consensus.

So now we have Alex, or rather, Regular Alex, Alex Up, and Alex Down. You know, no friction, sliding down (friction up), sliding up (friction down).

Ok, so, where next?

Drew. Drew Barrymore/Carey, Centers/Centres of Mass. What emerged here is the importance of setting it out the SAME way every time. Diagram in the middle, lambda top right, dm on the left, working out M_Total underneath. Every time. Don’t let them spatter gun it, it really won’t help later on. Cognitive load is reduced by doing it the SAME way. (You might get a student who says they don’t need to do it that way and they go off on their little tangent. That’s ok. I’ve have zero who have done that and not come back, but it you have one, yay! Would love to hear how they do it.)

Frankie…. goes to Hollywood. Or to the derivation of electric field using Coulomb’s Law.

Georgie – Gauss’s Law. That’s easy.

Harry… well, no. It then fell apart a bit because this morphed into Vic (potential, potential and capacitance). Followed by Iris (Biot-Savart), and Jordan (Ampere’s Law). These came a little late in the course to gain traction unlike Billy and Charlie.

Here’s the board that shows the fullest extent of our naming of equations.