How to use spaced repetition with the notes you already have

What is a spaced repetition schedule?

Spaced repetition means coming back to the same material several times, with gaps in between, instead of studying it once for a long stretch. A schedule is simply the plan for when those returns happen.

For lecture notes, a schedule that fits the research and a normal week looks like this: a short review the same day, another the next day or two, one about a week later, and one a few weeks after that, closer to the exam. Each review is a recall test from your notes, not a reread. The rest of this post explains where those gaps come from and how to adjust them.

Why spacing beats one long session

Forgetting starts quickly. A modern replication of Ebbinghaus's classic experiments reproduced the forgetting curve he described in the 1880s (Murre & Dros, 2015). The material was nonsense syllables, so it overstates how fast you'd forget a lecture you understood, but the shape is the point: you lose a lot early, then less and less.

Spacing your reviews works with that curve. A large review of the research found 839 assessments of distributed practice in 317 experiments, and concluded that the gap producing the most retention grew as the time until the test grew (Cepeda et al., 2006). A 2013 review of ten study techniques gave distributed practice one of its two high utility ratings, alongside practice testing (Dunlosky et al., 2013).

How long to wait between reviews

The most useful numbers come from a study in which more than 1,350 people learned a set of obscure facts, reviewed them after a gap of up to 3.5 months, and took a final test up to a year later (Cepeda et al., 2008). For test delays of 7, 35, 70 and 350 days, the gaps that gave the highest recall, among those tested, were 1, 11, 21 and 21 days.

Put as a proportion, the paper reports that the optimal gap declined from about 20 to 40% of a 1-week test delay to about 5 to 10% of a 1-year test delay. In plain terms: the further away your exam, the longer you can wait between reviews, but the gap shouldn't grow as fast as the exam date recedes.

• Exam in about a week: review the next day.
• Exam in about a month: leave roughly a week and a half between reviews.
• Exam in two or three months, or material you need for good: gaps of about three weeks.

These are rough guides from one study of trivia facts, not exact rules. Missing the ideal gap by a few days isn't a disaster either: in the same study, performance fell only gradually once the gap passed its ideal point.

A simple review calendar for your notes

1. 1Day 0, after the lecture: turn the note into questions. Write five to ten in the margin or at the top. This is your first review.
2. 2Day 1 or 2: cover the notes, answer the questions from memory, then check. Ten minutes per lecture is enough.
3. 3About a week later: answer the same questions again. Put a mark next to each one you missed.
4. 4About three weeks later, or a week before the exam if sooner: answer only the marked questions, plus a quick pass on the rest.
5. 5The last few days: mixed questions from every lecture, focusing on what you still miss.

In practice, put each review in your calendar on the day you write the note. "Biology L4, review 2" on Thursday is easier to keep than a vague plan to look back at things.

What a review session looks like

Open the note with the content hidden or scrolled out of view. Read a question, answer it out loud or on scrap paper, and only then look. Mark each question one of three ways: got it, shaky, or missed. Shaky counts as missed.

Say your physiology note has the question "What happens to blood pressure readings during exercise, and why?" If your answer stops at "systolic goes up", that's shaky. Check the note, say the full answer, and mark it for the next round.

What to do with what you miss

• Bring missed questions forward. Answer them again in two or three days instead of waiting for the next full review.
• Rewrite questions you keep missing. Often the question is vague, or it bundles two ideas.
• Retire questions you've answered correctly three times in a row. Move them to the final mixed review only.
• If a whole lecture is mostly misses, the issue is understanding, not memory. Ask about it, or relearn it, before spacing it.

Why spacing feels worse than cramming

Spacing feels less productive in the moment, because each review starts with some forgetting. In three flashcard experiments, spacing was more effective than massing for 90% of the participants, yet after the first study session, 72% of the participants believed that massing had been more effective (Kornell, 2009). The struggle to remember after a gap is part of what makes it work.

Spaced repetition without a flashcard app

Flashcard apps automate the timing, which is useful. But copying a semester of notes into cards takes hours, and it splits your material in two places. Using the notes themselves keeps the context: the diagram, the example, the lecturer's aside.

All you need is questions inside each note, a calendar entry for each review, and a mark for what you missed. If your notes live in Lumyo, you can choose which notes a chat reads, try to answer a question from memory, then ask and compare. Each answer cites its source and tapping it opens the exact line, so checking takes seconds. For a wider look at testing yourself from notes, see how to study from your own notes.