Spaced Repetition: The Smartest Way to Review Before an Exam

If you have ever crammed the night before an exam, passed, and forgotten everything a week later, you have met the forgetting curve. Spaced repetition is the simple, well-tested fix — and it is the difference between memorising for a test and actually keeping what you learn.

The forgetting curve, and why cramming fades

Hermann Ebbinghaus first mapped how memory decays over time in the 1880s: without review, we lose a large share of new information within days. Cramming — packing all your study into one massed session — fights a losing battle against this curve. It can get you through tomorrow’s exam, but the material drains away almost as fast as you learned it.

What spacing actually does

Distributed practice means spreading the same amount of study across several shorter sessions instead of one long one. Each time you return to a topic just as it is starting to fade, you interrupt the forgetting curve and reset it, so the memory decays more slowly the next time. A synthesis of 254 studies found that spaced practice reliably produces better long-term retention than massed practice (Cepeda et al., 2006), and it is one of the most robust findings in all of learning science. For the broader evidence on retrieval and spacing, see how to study smarter with AI.

How long should the gaps be?

There is no single magic interval, but the research gives a useful rule of thumb: the longer you need to remember something, the longer your gaps should be. In one large study, the best gap between sessions was roughly 10–20% of the time until the test — so for an exam in a month, reviewing every few days works well (Cepeda et al., 2008).

• Day 1: learn the material.
• Day 2: a quick review.
• A few days later: review again.
• About a week later: review again.
• Just before the exam: a final pass.

Flashcards make spacing effortless

Spaced repetition and flashcards are a natural pair. In a study specifically on flashcards, spacing the cards out beat cramming them — even though students often believe cramming feels more effective (Kornell, 2009). The catch is scheduling: doing it by hand is tedious, which is why most people give up.

How ScienceIQ handles the schedule for you

ScienceIQ turns your own lecture notes, slides, and documents into flashcards on the exam workspace, then surfaces each card right when you are about to forget it — so you get the benefit of spacing without tracking the calendar yourself. You just review what is due and let the schedule do the work. If you are still building the deck by hand, generate flashcards from the lecture PDF instead of typing every card.