The Feynman technique, explained by an undergrad who actually used it
I'd heard about the Feynman technique fourteen times before I tried it once. Here's why I think the explanations made it sound dumber than it is.
You've probably read this somewhere: "explain the concept to a 12-year-old." That's the Feynman technique. Cute, and not exactly useful, because in practice you don't have a 12-year-old, and even if you did, the question becomes whether you can fake it well enough that they don't ask follow-up questions.
The trick I'd missed is that the 12-year-old isn't the point. The constraint is. You're forcing yourself to use only words a 12-year-old already knows. That means no "matrix," no "oxidative phosphorylation," no "electron acceptor." It's astonishing how much of what we think is understanding turns out to be vocabulary.
The first time I tried it
It was the night before a Bio 101 midterm. I was supposed to know the Krebs cycle. I'd watched the lecture twice. I'd colored in a diagram. I sat down with a blank doc and tried to type out, in plain English, what happens.
“The Krebs cycle is in the mitochondria. It takes… something… and turns it into CO2 and ATP. I think there's NADH? It happens after glycolysis.”
That was as far as I got. Two sentences in I'd already hidden behind the word "something." I genuinely did not know what fed into the cycle. I had memorized the order of the stages without understanding what was traveling between them.
Re-reading would not have caught this. Highlighting would not have caught it. I would have walked into the exam confident, and bombed the one question that asked me to trace a carbon atom.
What I do now
I run a Feynman test after every lecture I record in Synapsi. The setup is dumb: I open a blank doc, I set a 10-minute timer, and I type as if I'm DMing my younger brother on a topic he's never heard of. When I hit a wall, I write "[GAP]" inline and keep going.
Then I look at the original material, but only at the parts that match my [GAP]s. The rest, I already knew. This is roughly half the studying I used to do, and the half I keep is the half that mattered.
The compounding effect is real. After about six weeks of doing this, I noticed I was reaching for the technique without setting up the doc, just running it in my head on the walk to class. That's when I trusted it. The 12-year-old never has to exist. You just have to take the constraint seriously.