Why answering questions beats re-reading your notes

Ask most people how they are preparing for a certification exam and they will tell you they are going over their notes. It feels like work, it feels like progress, and the material gets more familiar every pass. That last part is the problem. Familiarity is not the same as being able to produce an answer when the screen asks you a question, and the two come apart at exactly the wrong moment.

What the research actually compared

In a 2016 experiment published in Frontiers in Psychology, van Eersel and colleagues gave undergraduates a text and split them. One group re-read it. The other answered recall questions on it and got feedback. A week later both groups were tested. The group that had been made to retrieve the material remembered substantially more, with an effect size of 0.97 in the first experiment, which in this literature is a large difference rather than a marginal one.

Worth being precise about what that study is and is not. It is one experiment with 56 psychology undergraduates reading passages, not certification candidates sitting a timed exam. The reason it carries weight is that it sits on top of Roediger and Karpicke's 2006 work on test-enhanced learning, which it cites throughout, and which has been replicated for the better part of two decades. The direction is well established. The exact number is from one study.

Spacing does the other half of the work

The second finding is about when you practise rather than how. A 2025 meta-analytic review in Behavioral Sciences pulled together 22 studies of distributed practice and found a moderate advantage for spreading study out over cramming it together, with an effect size of 0.54. What makes that review useful is its restriction: it deliberately excluded laboratory experiments and looked only at classroom studies using real curriculum material, which is a much harder test than memorising word pairs in a lab.

What that looks like in a week

1. Start a session with questions on what you covered two or three days ago, before you touch anything new.
2. Read the explanation on every question you got wrong, and on every one you guessed correctly.
3. Keep sessions short and frequent. Four evenings of twenty minutes beats one evening of eighty.
4. In the last fortnight, sit at least one full length timed exam so the clock is not a new variable on the day.

The honest limit

Effect sizes are averages across groups, not promises to an individual. Neither study above tested IT certification candidates, and the second one is a review of classroom learners rather than adults revising alone after work. What the evidence supports is the direction: retrieval beats re-reading, and spaced beats massed. How much it moves your score depends on where you are starting and how honestly you mark yourself wrong.