How to Do Active Recall (and Why Rereading Doesn't Work)

Active recall means testing yourself instead of reviewing: you close the notes, ask yourself a question, and try to pull the answer out of your own memory before you check it. To do it, turn what you are studying into questions, answer them without looking, check, and come back to the ones you missed a few days later.

That is the whole idea. The rest of this article is how to do it with an actual lecture, and why it works better than the thing most students do instead: reading their notes again.

What active recall is (and what it is not)

There are two ways to "know" something:

• Recognition: you see the answer and think "yes, I know that." Rereading your notes, highlighting, and watching the lecture again all run on recognition.
• Recall: nothing is in front of you, and you have to produce the answer yourself. An exam runs on recall.

Active recall is practicing the second one. If the notes are open while you "study," you are practicing recognition, however hard you concentrate.

A quick test: cover the page, and say out loud what the last section was about. If you can, that was recall. If you reach for the page, that is the gap the exam will find.

Why rereading feels better but works worse

Rereading feels productive because the material gets more familiar every time. Familiar feels like learned. It isn't the same thing.

Researchers have tested this directly. In a well-known study, students read a short passage and then either reread it several times or tried to recall it several times. Five minutes later the rereaders remembered more. One week later it flipped: the students who practiced recalling remembered about 61% of the passage, the rereaders about 40% (Roediger & Karpicke, 2006).

The same pattern shows up again and again:

• A large review of ten common study techniques rated practice testing and spaced practice as the two most useful, and rereading and highlighting as low-utility (Dunlosky et al., 2013).
• Students learning foreign-language word pairs who kept testing themselves on pairs they had already gotten right remembered far more a week later than students who stopped testing those pairs and only restudied them (Karpicke & Roediger, 2008).
• Even so, when college students were asked how they study, most said rereading, and over half named it as their main strategy (Karpicke, Butler & Roediger, 2009).

So the problem is not that students don't work hard. It's that the most common way of working hard trains the wrong skill.

How to do active recall: six ways

You don't need a special system. Any of these counts, as long as you answer before you look.

1. The blank page

Close everything. On a blank page, write down everything you remember about one topic: definitions, steps, diagrams, examples. Then open your notes and mark what you missed or got wrong in a different color. Those gaps are your next study session.

This is the fastest way to start, and the most uncomfortable, which is a good sign.

2. Questions in the margin

As you go through your notes, write a question next to each chunk: "What does the sodium-potassium pump do?", "Why is the derivative of a constant zero?" Later, cover the notes and answer only from the questions. (This is what the left column of Cornell notes is for.)

3. Flashcards, used properly

Flashcards are active recall if you say the answer before you flip. They stop being active recall when you flip after a second and think "yeah, I knew that."

• Put one idea on each card. "Explain the Krebs cycle" is not a flashcard; "What molecule enters the Krebs cycle?" is.
• Go both directions for terms: term → definition and definition → term.
• Don't drop a card the first time you get it right. Keep it in rotation, just less often.

If you want to make cards quickly and print them, our free flashcard maker does that with no account.

4. Practice problems and old exams

In math, physics, chemistry and economics, the questions are the content. Do problems from the end of the chapter or old exams without looking at the worked example first. If you get stuck, look at only the next step, close it, and keep going.

5. Teach it out loud

Explain the topic to a friend, a roommate, or an empty room, without notes. The places where you start to say "it's kind of like…" are the places you don't know yet. This is sometimes called the Feynman technique.

6. Turn the slide titles into questions

Lecture slides are already an outline. Read only the title of a slide, close it, and explain what was on it. We wrote a whole guide on this: how to study lecture slides.

A routine for one lecture

Here is what active recall looks like over a week, for one lecture:

1. Same day (10 minutes). Blank page: write what you remember from the lecture. Check against the slides. Write questions next to the parts you missed.
2. Next day (10 minutes). Answer the questions without notes. Make flashcards for the terms you keep missing.
3. Three or four days later (10 minutes). Cards plus two or three practice problems.
4. One week later (10 minutes). Blank page again, for the whole lecture. Compare it with the first one.

Forty minutes in total, spread out. The spreading out matters as much as the testing. Memory fades between sessions, and pulling it back each time is what makes it last. Spacing your practice out is one of the most reliable findings in learning research (Cepeda et al., 2006).

If you have a fixed exam date and several topics, our free study schedule maker lays these review sessions out day by day.

Common mistakes

• Peeking too soon. Give yourself 10 to 20 seconds of real effort before you check. The effort is the point.
• Only recognizing. Multiple-choice self-quizzes help, but they let you recognize the answer. Mix in questions where you have to write it.
• No checking. Recall without checking can lock in a wrong answer. Always look after you answer.
• Retiring cards too early. Getting it right once today doesn't mean you'll get it right in two weeks.
• Cramming the recall. Ten sessions the night before is better than rereading, but the same ten sessions spread over two weeks is much better.

Active recall and spaced repetition

They are two halves of one habit. Active recall is how you review: by testing yourself. Spaced repetition is when you review: just as you are starting to forget, with the gaps getting longer each time you get it right. Flashcard apps like Anki do the "when" for you; you still have to do the "how" honestly.

Questions students ask

Is active recall better than rereading? For anything you'll be tested on later, yes. Rereading wins only if the test is in the next few minutes.

How long should an active recall session be? Short. Ten to twenty-five minutes on one topic is plenty; then switch topics or take a break.

Does it work for subjects like math? Yes. In math it looks like doing problems without the worked example open, which is exactly what the exam asks you to do.

Is it normal that it feels harder than rereading? Yes. If it feels easy, you are probably recognizing, not recalling.