Taking a Quiz Teaches You More Than Rereading Your Notes, and Scientists Know Why
Picture the night before an exam, a licensing test, or a big presentation at work. The notes are open, the highlighter is out, and you read the same pages for the third time. Everything looks familiar. You feel ready. Then the real questions arrive and half of what you "knew" is suddenly out of reach.
That gap between feeling prepared and actually being able to remember has been studied for more than a century. The research points to a surprisingly simple fix: stop rereading so much and start quizzing yourself. Psychologists call it the testing effect, or retrieval practice, and it is one of the most reliable findings in the science of learning. Below, I explain what the key experiments found, why pulling information out of your head works better than pouring it back in, and how to use this in school, at work, or just for the pleasure of knowing more.
Key Takeaways
- Trying to recall information strengthens memory more than reading it again, even when no one tells you whether your answers were right.
- In a landmark 2006 study, students who practiced recalling a passage remembered 61% of it a week later, compared with 40% for students who reread it, despite reading it far fewer times.
- Rereading creates a feeling of familiarity that people mistake for knowledge, which is why it feels productive.
- Major reviews rate practice testing as one of the most effective study methods available, while rereading and highlighting rank near the bottom.
- Quizzing works best when it is low-stakes, followed by checking the answers, and repeated over days rather than crammed into one sitting.
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What Is the Testing Effect?
The testing effect is the finding that the act of retrieving information from memory makes that information easier to remember later. A test is usually thought of as a measuring stick: it tells you what you know. The research shows it is also a learning tool. Each time you successfully dig up a fact, a name, or an idea, you change the memory itself and make it more durable.
This is not a new idea. In 1917, the American educational psychologist Arthur Gates published a study called "Recitation as a Factor in Memorizing," which found that students who spent part of their study time reciting material from memory did better than those who spent all their time reading. For decades afterward, the finding surfaced now and then in research journals without changing how most people studied. As late as 1989, a paper by John Glover carried a title that summed up the situation well: the testing phenomenon was "not gone but nearly forgotten."
What revived it was a series of carefully designed experiments in the 2000s that used realistic study materials instead of word lists, and that compared testing directly with the strategy most students actually use: reading the material again.
02
The Experiment That Changed the Conversation
In 2006, psychologists Henry L. Roediger III and Jeffrey D. Karpicke of Washington University in St. Louis published a short paper in Psychological Science titled "Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention." It has since become one of the most cited studies in educational psychology.
The setup was simple. College students read short science passages of about 260 to 275 words, one on the sun and one on sea otters, taken from an English-proficiency test prep book. In the first experiment, students read a passage and then either read it again or took a recall test in which they wrote down everything they could remember. Nobody received feedback on what they got right or wrong.
Five minutes later, the rereaders did slightly better (81% vs. 75% of the ideas recalled). But when the final test came two days later, the pattern flipped: the tested group recalled 68% versus 54%. After one week, it was 56% versus 42%. In effect, one practice test held off forgetting for about five extra days.
More reading vs. more recalling
The second experiment pushed the comparison further. Students spent four short sessions with a passage in one of three ways:
| Study pattern | Times the passage was read | Recall after 5 minutes | Recall after 1 week |
|---|---|---|---|
| Read, read, read, read | About 14 | 83% | 40% |
| Read, read, read, recall | About 10 | 78% | 56% |
| Read, recall, recall, recall | About 3 | 71% | 61% |
Source: Roediger & Karpicke (2006), Experiment 2. Figures rounded.
Read that table twice, because it is the heart of the whole story. The students who read the passage roughly 14 times looked like the winners at first. A week later, they remembered the least. The students who read it only about three times, and spent the rest of their time trying to recall it, remembered the most.
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Why Rereading Feels Effective but Isn't
The same study included a detail that explains why so many of us keep rereading anyway. After the learning session, students rated how well they expected to remember the passage a week later. The repeated readers were the most confident group, giving an average of 4.8 on a 7-point scale, compared with about 4.0 for the repeated-recall group. They turned out to be the worst performers.
Psychologists often describe this as an illusion of fluency. When you read something for the second or third time, it flows easily. You recognize every sentence. That smooth, familiar feeling is easy to confuse with mastery. But recognizing information when it is right in front of you is a very different skill from producing it when the page is closed, which is what an exam, a client meeting, or a conversation usually demands.
Rereading is like watching someone else lift weights. It looks easy and you understand the motion, but your own muscles have not done the work. Recalling from memory is lifting the weight yourself.
Rereading has another hidden cost: it gives you no honest feedback. A quiz shows you instantly which parts you cannot recall. Rereading lets the weak spots hide behind the familiar parts.
04
Why Quizzing Works: What Scientists Have Found
Researchers do not think there is a single switch that explains the testing effect. Several mechanisms seem to work together. Here are the ones with the strongest support.
1. Retrieval strengthens the path back to the memory
A memory is only useful if you can find it when you need it. UCLA psychologist Robert Bjork suggested decades ago that each act of retrieval adds or reinforces the routes that lead back to a stored piece of information. Reading puts information in front of you; recalling makes you practice the exact journey you will need to make later.
2. Useful struggle, or "desirable difficulties"
Bjork and his colleague Elizabeth Bjork, whose Learning and Forgetting Lab at UCLA has studied this for years, coined the term desirable difficulties. It refers to learning conditions that slow you down or feel harder in the moment but produce stronger long-term memory. Retrieval practice is a classic example. The mild effort of searching your memory is part of what makes the memory stick. Rereading, by contrast, is easy, and that ease is exactly why it does less.
The Bjorks also distinguish between two kinds of memory strength. Retrieval strength is how easily you can bring something to mind right now. Storage strength is how deeply it is rooted. Rereading boosts the first temporarily, which is why you feel ready. Effortful recall builds the second, which is what lasts.
3. Practicing the skill you will actually need
Roediger and Karpicke pointed to a principle called transfer-appropriate processing: you perform best when the way you practice matches the way you will be tested. If you will need to recall information from memory later, practicing recall now is simply better preparation than practicing recognition.
4. A built-in progress report
Quizzes also help indirectly. They reveal what you do not know, so you can spend your time where it matters. They also tend to push people to spread their studying out instead of cramming, which is itself one of the most effective learning strategies known.
05
Once You Know It, Test It Again
A common assumption is that once you get an answer right, you can move on. A 2008 study in Science by Karpicke and Roediger, "The Critical Importance of Retrieval for Learning," put that assumption to the test.
Students learned 40 Swahili–English word pairs through rounds of study and testing. Once a student correctly recalled a pair, the researchers either kept it in future study rounds, kept it in future test rounds, kept it in both, or dropped it entirely. One week later, students who had continued to be tested on pairs they already knew recalled about 80% of them. Students for whom those pairs were dropped from testing recalled only about 36% and 33%, even when they kept restudying them.
Getting something right once is not the finish line. Repeated recall after you already "know" something is what locks it in. Extra reading at that stage added almost nothing.
Just as telling, the students' predictions of how well they would do were unrelated to how well they actually did. Even university students, it seems, have poor intuitions about which study methods work.
06
It's Not Just for Memorizing Facts
A fair objection is that quizzing might help with vocabulary and trivia but not with real understanding. A 2011 study in Science by Karpicke and Janell Blunt, "Retrieval Practice Produces More Learning than Elaborative Studying with Concept Mapping," tackled that directly.
Students read science texts and then either practiced recalling the material or built concept maps, diagrams that link ideas together and are widely used in classrooms to encourage deeper thinking. A week later, the retrieval practice group did better not only on questions about facts but also on questions that required inference, meaning applying the ideas rather than repeating them. Remarkably, retrieval practice still came out ahead when the final test itself asked students to draw a concept map. Students in the study had predicted the opposite.
In fairness, not everyone was convinced. Critics writing in Science later that year argued that students had received too little training in concept mapping for a fair comparison. That is a reasonable point, and it is a reminder that concept mapping still has value. But the broader conclusion, that recall supports understanding and not just rote memory, has been supported by many later studies.
07
The Evidence Beyond One Lab
One striking experiment can be a fluke. What makes the testing effect so credible is how often it has been reproduced, by different researchers, with different people and materials.
A major review of study techniques
In 2013, a team led by Kent State University psychologist John Dunlosky reviewed the evidence for ten popular study techniques in the journal Psychological Science in the Public Interest. Only two earned their top rating of "high utility": practice testing and distributed practice (spreading study over time). Rereading and highlighting, the two methods students report using most, received low ratings because they do not reliably improve performance. The authors explicitly recommended practice testing in place of rereading. A readable summary is available from the American Federation of Teachers.
A meta-analysis across many studies
A 2017 meta-analysis by Olusola Adesope and colleagues in the Review of Educational Research, "Rethinking the Use of Tests," pooled results from a large body of experiments. Practice tests outperformed restudying with a moderate effect size (about 0.51) and outperformed doing nothing or doing unrelated filler tasks by a large margin (about 0.93). The benefits appeared across age groups, from elementary school through university.
Real classrooms, real grades
Lab results do not always survive contact with a real school. So Roediger, Pooja Agarwal, Mark McDaniel, and Kathleen McDermott ran a series of experiments in sixth-grade social studies classes. Their 2011 paper, "Test-Enhanced Learning in the Classroom," found that short, low-stakes quizzes improved performance on chapter exams and end-of-semester exams, compared both with material that was not quizzed and with material students simply reread. A related study in middle school science found similar gains and noted that short-answer quizzes produced more robust benefits than multiple-choice ones.
Memory under pressure
A 2016 study in Science by Amy Smith, Victoria Floerke, and Ayanna Thomas at Tufts University reported that people who learned material through retrieval practice did not show the usual drop in memory after being put through a stressful task, while people who learned by rereading did. It is an encouraging result for anyone who freezes during exams. However, later researchers have noted that this particular finding has been difficult to replicate consistently, so it is best treated as promising rather than settled.
08
Rereading vs. Quizzing at a Glance
| Rereading | Quizzing yourself | |
|---|---|---|
| How it feels | Smooth, comfortable, productive | Effortful, sometimes frustrating |
| Short-term results | Often slightly better within minutes | Slightly lower right away |
| Results after days or weeks | Much more forgetting | Substantially better retention |
| Feedback on what you know | Almost none | Immediate and honest |
| Confidence | Often overconfident | More realistic |
| Research rating | Low utility (Dunlosky et al., 2013) | High utility (Dunlosky et al., 2013) |
09
When Quizzing Works Best, and When It Doesn't
Retrieval practice is powerful, but it is not magic. The research points to a few conditions that make a real difference.
- Check your answers. The classic experiments worked even without feedback, but feedback makes quizzing more effective and prevents you from locking in mistakes. This matters especially with multiple-choice questions, where a wrong option you chose can linger in memory if it is never corrected.
- Aim for "hard but doable." If questions are so difficult that you recall almost nothing, you have little to strengthen. If they are too easy, there is no useful effort. You need a foundation first; quizzing works best after you have studied the material at least once.
- Prefer producing over picking. Writing or saying an answer from scratch generally builds stronger memory than choosing from options, though multiple-choice quizzes still help, particularly when you review the correct answers.
- Space it out. Recalling something once today and again a few days later beats recalling it five times in a row tonight. Testing and spacing reinforce each other.
- Keep the stakes low. The benefit comes from the act of retrieval, not from grades. As researchers who study this often stress, the goal is frequent, low-pressure practice, not more high-stakes exams.
10
How to Use Retrieval Practice in Everyday Life
You do not need special software or a classroom to use this. Here are simple ways to turn any study session, or any bit of curiosity, into retrieval practice.
- Try the blank-page methodAfter reading a chapter, article, or report, close it and write down everything you remember. Then open it again and compare. The gaps you find are your to-do list.
- Turn headings into questionsConvert each section title in your notes into a question ("What causes inflation?") and answer it out loud before looking at your notes.
- Use flashcards honestlySay or write the answer before flipping the card. Keep cards you have already answered correctly in the deck and revisit them later instead of retiring them after one success.
- Spread your sessionsReview new material the next day, again a few days later, and again the following week. The exact intervals matter less than coming back after some forgetting has begun.
- Explain it to someoneTeaching a friend or colleague forces you to retrieve and organize ideas without looking. If you cannot explain it simply, you have found what to review.
- Make quizzing a daily habitShort general-knowledge quizzes are an easy, enjoyable form of retrieval practice. A daily set such as Today's Bing Quiz or the Bing News Quiz gives you a few minutes of recall practice and shows you what has actually stuck from the news and facts you come across.
The same principle applies well beyond school. Whether you are learning new accounting rules, product details, a software tool, or talking points for a meeting, a few minutes of recalling the key points without notes will serve you better than reading the same slides one more time.
Test Yourself: 3 Quick Questions
Since you have just read about retrieval practice, try it. Answer each question in your head before tapping to reveal.
In the 2006 study, which group remembered the most after one week?
The group that read the passage once and then practiced recalling it three times. They remembered about 61%, compared with 40% for the group that only reread it.
Why does rereading feel more effective than it really is?
Because familiar material feels fluent and easy, and people mistake that sense of recognition for the ability to recall it later. Repeated readers in the study were the most confident and performed the worst.
What did the 2008 Swahili vocabulary study show about items you already know?
Continuing to test yourself on them keeps them in memory (about 80% recalled a week later), while dropping them from testing led to much lower recall, even with extra studying.
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Frequently Asked Questions
Is retrieval practice the same as the testing effect?
They describe the same phenomenon from two angles. "Testing effect" is the name for the finding that tests improve memory. "Retrieval practice" is the name for the study strategy of deliberately recalling information to take advantage of that effect.
Does rereading have any value at all?
Yes. Reading material carefully the first time is essential, and a quick reread can help you check what you missed after a quiz. The problem is relying on repeated rereading as your main study method, because it produces weak long-term retention compared with recall.
Do multiple-choice quizzes work, or only written answers?
Both help. Research generally finds that producing an answer from memory, as with short-answer questions, gives a stronger boost, but multiple-choice quizzes also improve retention, especially when you check the correct answers afterward.
What if I get a lot of questions wrong?
That is normal and useful. A failed attempt shows you exactly what to review, and some studies suggest that trying to answer before you know the material can even make later studying more effective. Just make sure you look up the right answers so errors do not stick.
Does this work for adults, or only for students?
The testing effect has been found in children, university students, and adults, across subjects ranging from science and history to foreign vocabulary. The underlying memory processes do not stop working after graduation.
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Final Thoughts
The most useful lesson from this research may be about trusting our own sense of what works. Rereading feels productive, and quizzing feels uncomfortable, yet the evidence consistently points the other way. More than a century after Arthur Gates first noticed the benefits of recitation, and two decades after Roediger and Karpicke's experiments brought the idea back into focus, the message from the science is clear: the effort of remembering is not a sign that learning is failing. It is the learning.
So the next time you reach for your notes to read them again, close them instead and ask yourself what you remember. It will feel harder. That is the point.
Sources and Further Reading
- Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255. doi.org/10.1111/j.1467-9280.2006.01693.x
- Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966–968. doi.org/10.1126/science.1152408
- Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772–775. doi.org/10.1126/science.1199327
- Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58. doi.org/10.1177/1529100612453266
- Adesope, O. O., Trevisan, D. A., & Sundararajan, N. (2017). Rethinking the use of tests: A meta-analysis of practice testing. Review of Educational Research, 87(3), 659–701. doi.org/10.3102/0034654316689306
- Roediger, H. L., Agarwal, P. K., McDaniel, M. A., & McDermott, K. B. (2011). Test-enhanced learning in the classroom: Long-term improvements from quizzing. Journal of Experimental Psychology: Applied, 17(4), 382–395. PDF
- Smith, A. M., Floerke, V. A., & Thomas, A. K. (2016). Retrieval practice protects memory against acute stress. Science, 354(6315), 1046–1048. doi.org/10.1126/science.aah5067
- Bjork, E. L., & Bjork, R. A. (2011). Making things hard on yourself, but in a good way: Creating desirable difficulties to enhance learning. Bjork Learning and Forgetting Lab, UCLA (PDF)