Retrieval means deliberately dredging up knowledge from your mind—not just passively exposing yourself to it.

Countless studies show retrieval practice works better than passive review . If you’re going to use the knowledge in a specific place, practice in that place. Do practice tests, work on real problems and apply it.

Spacing is the idea of repeated reviews, spread out in time . It’s one of the most robust effects in cognitive psychology, benefiting many subjects.