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Retrieval practice and study spacing are two very effective learning strategies. A review of several scientific articles indicates that the benefits of these methods do not depend on the level of education or discipline. Combining these two practices might event create a super strategy with guaranteed results.

Testing knowledge while learning and distributing the study over time are two strategies supported by psychological science that can improve learning at all ages and in various fields: this is the conclusion of a literature review published recently by the journal Nature. This review of several studies, conducted by Shana Carpenter (Iowa State University), Steven Pan (University of Singapore) and Andrew Butler (Washington University in St. Louis) reinforces the value of retrieval practice (how to study) and spacing (when to study) applied to all levels of education and subjects, from preschool to college, from reading to math and science.


Spaced study consists of establishing time intervals between study sessions. To understand the effects of spacing on learning, researchers typically compare two groups of participants: one who had at least two study opportunities in a row (blocked study) with another who had study opportunities separated in time (spaced study).

Carpenter and colleagues selected 46 studies showing significant advantages of spacing in learning when compared with blocked study. These publications indicate the benefits of spacing occur at different ages, from preschool to adulthood (over 50 years), at all levels of education, and for various learning materials — including toy names, grammar rules, mathematics, biology, foreign languages, surgical procedures — or even motor skills. It should be noted that these studies follow different schedules of spacing implementation, ranging from 15 minutes to 1 month. These results indicate the power of this learning strategy, which works in any grade and for any subject.

Retrieval practice

Retrieval practice consists of repeated testing and is usually compared with more passive strategies, such as rereading materials. However, even when compared with so-called more active strategies, such as the creation of concept maps or note taking in the presence of the material to be apprehended, retrieval practice also proves to be more effective.

Carpenter and colleagues selected 53 studies showing significant advantages of retrieval practice in learning. Similar to the findings on spacing, retrieval practice favors learning at all ages, from preschool to seniority (from 18 months to well after 60 years); at all levels of education; for various learning topics, including reading, mathematics, science, or medicine; and with different types of tests: free recall, multiple choice, filling-in spaces, true or false questionnaires, in virtual mode, and even in games that incorporate information retrieval. These results reinforce the idea that retrieval practice is probably the most powerful learning strategy for any student in any context.

Successive relearning: the super strategy

What happens when you combine two such powerful learning strategies. An even more effective strategy is obtained: successive relearning, described by Rawson and Dunlosky. Successive relearning implies a first session in which students retrieve the information to be learned through a test that is evaluated. This initial session is followed by relearning sessions, in successive cycles until students achieve a predetermined criterion, such as a certain total of correct answers. Learning is most effective when relearning sessions are separated in time and when the first session includes additional retrieval practice, such as answering each question three times correctly.

How to implement the best strategies

Despite the potential of these strategies, students do not often use them. The use of effective learning strategies depends on students’ metacognition, that is, on their ability to self-assess their knowledge and use this information to decide how and how much to study. The main obstacle to the adoption of strategies as effective as successive relearning or its two components, retrieval practice and spacing, is the effort that their planning and implementation require. In addition, these strategies can also be difficult to maintain because they may seem counterintuitive, since the results in the first tests tend to be low and, because of the spacing, a student might initially feel that they are unlearning.

In their article, Carpenter and colleagues offer some tactics for students to improve their metacognition or, in other words, learn to know what they know and what they don't know and to evaluate how much they learn with different methods so that they can then regulate their study decisions in order to adopt the best ones:

  1. Clearly explain to students the efficacy of different study strategies.
  2. Deconstruct myths and wrong beliefs about learning. For example, combat illusions that occur when the strategy used seems to simplify the information to be learned, but in reality, it does not foster learning (e.g., reading the same thing several times).
  3. Work with students to plan their study, so that they understand different ways of using the same strategy and which are more favorable, considering factors such as the complexity of the different subjects and the type of final test.
  4. Teach students to monitor their progress by making regular metacognitive judgments: how complex is the material to be learned? What is well-learned and what needs to be worked on? How good are their answers? These judgments inform how to allocate study time to different materials and can be used to increase students' motivation and interest.

In sum, Carpenter and colleagues highlight two learning strategies so powerful that they work with diverse materials and at all levels of education. However, their usefulness depends on students’ ability to evaluate the progress of their learning and to create a study plan and routine that makes good use of these strategies.


Carpenter, S. K., Pan, S. C., & Butler, A. C. (2022). The science of effective learning with spacing and retrieval practice. Nature Reviews Psychology, 1-16.

Rawson, K. A., & Dunlosky, J. (2022). Successive relearning: an underexplored but potent technique for obtaining and maintaining knowledge. Current Directions in Psychological Science31(4), 362-368.

Rawson, K. A., & Dunlosky, J. (2011). Optimizing schedules of retrieval practice for durable and efficient learning: How much is enough?. Journal of Experimental Psychology: General140(3), 283.


Ludmila D. Nunes is the Senior Director for Science Knowledge and Expertise at the American Psychological Association (APA). She holds a PhD in Psychology from the University of Lisbon, and has conducted research in human memory and learning at Washington University in St. Louis, Purdue University, and the University of Lisbon. In addition to her research, she has taught classes in Cognitive Psychology and Human Memory at Purdue University, has been a reviewer for several scientific publications, and a science writer.

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