How to Learn (the highest-leverage skill)

The board behind almost every other lesson in this site: why something you read once fades, and what makes it stick instead. It builds on how memory works (How Memory Works) and points deliberate practice (Deliberate Practice (how expertise is actually built)) at knowledge instead of skill.

Before you start. Deliberate practice said a skill grows at the edge of what you can already do, with fast feedback on exactly what went wrong, never from the easy rep. This lesson makes the same claim about knowledge: the study method that feels like it’s working is usually the one that isn’t.

The idea in 30 seconds

Rereading feels productive right away and loses within a week; closing the book and forcing out the answer (retrieval) loses at first and wins after.
Familiarity is not the same thing as being able to produce an answer, and studying for familiarity alone hides the gap until a real test finds it.
Spaced repetition means reviewing near the point you would otherwise forget, not right after you learn something and not so late there’s nothing left to retrieve.
Mixing problem types in one session (interleaving) scores worse during practice, then wins by a wide margin on a later test where the types come shuffled and you must first pick the method.
Elaboration connects a new fact to what you already know; explaining it in plain words to someone who knows less (the Feynman technique) finds the exact gap in your understanding.

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