Ask "why this and not that?"

Explain why a fact is true rather than a plausible alternative.

Why it works

Explaining why something is true while a close alternative is false forces discrimination — you must identify the feature that actually decides the case. That contrast sharpens the concept and protects against the illusion that you understand it just because the single correct answer sounds familiar. Knowing why the wrong answer is wrong is a stronger test of understanding than knowing the right one.

How to do it

1. For each fact, name a plausible alternative that turns out to be false.
2. Explain the specific reason the true version holds and the alternative does not.
3. Use the deciding feature as your memory hook for the fact.

Evidence

Comparison and contrasting cases are well supported in learning research for building flexible, transferable understanding, and align with the elaboration principle that meaningful distinctions encode better than isolated facts. Gentner, Loewenstein, and Thompson found that comparing two cases side by side — analogical encoding — helped learners extract the shared principle and transfer it to new problems far more than studying the same cases separately. (rct)

This applies established comparison and self-explanation findings; the "why this not that" framing is a practical operationalization rather than a separately validated technique.

Sources

• Gentner, D., Loewenstein, J., & Thompson, L. (2003). Learning and transfer: A general role for analogical encoding. Journal of Educational Psychology, 95(2), 393-408.

Common mistake

Only ever explaining why the right answer is right, never why the tempting wrong one is wrong, leaving you unable to tell them apart under pressure.