Revision that works: test yourself, space it out
The techniques most students use are the ones that perform worst. The two that win are both slightly unpleasant, which is the whole problem.
The finding everyone should know
In 2013 a team of psychologists led by John Dunlosky reviewed ten common study techniques and graded each on how well the evidence supported it. The paper, Improving Students’ Learning With Effective Learning Techniques, published in Psychological Science in the Public Interest, is worth knowing about because its conclusions are so unflattering to normal revision habits.
Two techniques were rated high utility:
- Practice testing, meaning retrieving information from memory rather than reviewing it.
- Distributed practice, meaning spreading study over time instead of massing it.
Rated low utility, among others: highlighting and underlining, re-reading, and summarising. Which is to say: the three things most people do most of the time.
Why re-reading fools you
Read a page twice and the second pass is easier. It feels familiar and it goes quickly, and your brain reads that fluency as a signal that you know it. You do not. You have learned to recognise the material, which is a much weaker thing than being able to produce it, and recognition is not what an exam asks for.
This is why revision can feel productive for six hours and leave nothing behind. The feeling being tracked is ease, and ease is close to the opposite of what builds memory.
Testing yourself is the strong one
The classic demonstration is by Henry Roediger and Jeffrey Karpicke, published in Psychological Science in 2006. Students read passages, then either re-read them or took a test on them. On an assessment shortly afterwards, the re-readers looked better. On a delayed test days later, which is the case that actually matters, the tested group was substantially ahead.
Two things worth taking from that. First, the effect is about durable memory, so any short comparison you run on yourself will mislead you. Second, the test is not the measurement. The act of dragging something out of memory is what strengthens it. This is called the testing effect, and it is one of the most reliably reproduced findings in the field.
What it looks like in practice
- Closed-book recall. Shut the book and write everything you can about the topic. Then open it and mark your own gaps in a different colour. The gaps are the revision.
- Past paper questions, answered under something like real conditions before you look at the mark scheme.
- Flashcards, used properly. Answer out loud or in writing before turning the card over. Flipping through and thinking “yes, I know that one” is re-reading with extra steps.
- Explain it to someone who does not know it, without notes. You find the holes within about a minute.
Spacing it out is the other one
The same total revision time produces more durable memory split across several days than piled into one. Cramming genuinely works for tomorrow morning, which is why it survives, and then falls off a cliff. That is a catastrophe if the same content reappears in a paper three months later.
You do not need an elaborate algorithm. Revisit a topic the next day, then a few days later, then a week or two after that. Expanding gaps, roughly. The important part is to come back to it after you have started to forget. The small struggle to retrieve it is the mechanism, so making it too easy defeats the exercise.
And mix things up
Interleaving, meaning mixing question types within a session rather than doing thirty of the same kind, tends to produce better performance later, though it feels worse at the time and results are more mixed than for testing and spacing. Doing thirty identical problems lets you stop deciding which method applies, which is precisely the decision an exam requires.
The pattern behind all three: the techniques that feel harder in the moment tend to be the ones that work, and the ones that feel smooth tend not to. Your sense of how well revision is going is close to inverted.
Fitting it into 25-minute blocks
- Minutes 0 to 3. Before opening anything, write what you already remember about today’s topic. This is a test, and it tells you where to spend the round.
- Minutes 3 to 20. Work on the gaps: notes, textbook, worked examples, whatever the subject needs.
- Minutes 20 to 25. Books shut. Write it out again from memory. Compare.
- Tomorrow. Start the next session with two minutes of recall on yesterday’s topic before touching today’s. That is your spacing, and it costs almost nothing.
Four rounds like that is a serious afternoon’s revision, and it will feel considerably less comfortable than four hours of highlighting. That is the trade.