Spaced repetition vs cramming: what the research says

Hermann Ebbinghaus discovered the 'forgetting curve' in 1885: without review, we forget about half of what we learn within an hour, and 70% within a day. Cramming the night before an exam works just well enough that we keep doing it, but the material is gone within a week.

Spaced repetition flips that. By reviewing material at increasing intervals — one day, three days, a week, a month — you re-set the forgetting curve every time. Each review is shorter than the last, and the material moves into long-term memory.

A 2013 meta-analysis covering more than 14,000 students found spaced practice produced significantly better long-term retention than massed practice (cramming) across every subject and age group studied. The effect was largest for material that needs to be remembered for more than a few days — exactly the situation most students are in.

The downside: it requires planning. You can't decide to use spaced repetition the night before. That's why every effective spaced-repetition tool — Anki, Quizlet, My-Prompt's flashcards — schedules reviews for you. Trust the algorithm; do the reviews when it asks; the rest takes care of itself.