Here’s a study that may surprise you. A group of eight-year-olds practiced tossing beanbags into buckets in gym class. Half of the kids tossed into a bucket three feet away. The other half mixed it up by tossing into buckets two feet and four feet away. After twelve weeks of this they were all tested on tossing into a three-foot bucket. The kids who did the best by far were those who’d practiced on two- and four-foot buckets but never on three-foot buckets.

Why is this? We will come back to the beanbags, but first a little insight into a widely held myth about how we learn.

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The Myth of Massed Practice

Most of us believe that learning is better when you go at something with single-minded purpose: the practice-practice-practice that’s supposed to burn a skill into memory. Faith in focused, repetitive practice of one thing at a time until we’ve got it nailed is pervasive among classroom teachers, athletes, corporate trainers, and students. Researchers call this kind of practice “massed,” and our faith rests in large part on the simple fact that when we do it, we can see it making a difference. Nevertheless, despite what our eyes tell us, this faith is misplaced.

If learning can be defined as picking up new knowledge or skills and being able to apply them later, then how quickly you pick something up is only part of the story. Is it still there when you need to use it out in the everyday world? While practicing is vital to learning and memory, studies have shown that practice is far more effective when it’s broken into separate periods of training that are spaced out. The rapid gains produced by massed practice are often evident, but the rapid forgetting that follows is not. Practice that’s spaced out, interleaved with other learning, and varied produces better mastery, longer retention, and more versatility. But these benefits come at a price: when practice is spaced, interleaved, and varied, it requires more effort. You feel the increased effort, but not the benefits the effort produces. Learning feels slower from this kind of practice, and you don’t get the rapid improvements and affirmations you’re accustomed to seeing from massed practice. Even in studies where the participants have shown superior results from spaced learning, they don’t perceive the improvement; they believe they learned better on the material where practice was massed.

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Almost everywhere you look, you find examples of massed practice: colleges that offer concentration in a single subject with the promise of fast learning, continuing education seminars for professionals where training is condensed into a single weekend. Cramming for exams is a form of massed practice. It feels like a productive strategy, and it may get you through the next day’s midterm, but most of the material will be long forgotten by the time you sit down for the final. Spacing out your practice feels less productive for the very reason that some forgetting has set in and you’ve got to work harder to recall the concepts. It doesn’t feel like you’re on top of it. What you don’t sense in the moment is that this added effort is making the learning stronger.

Spaced Practice

The benefits of spacing out practice sessions are long established, but for a vivid example consider this study of thirty-eight surgical residents. They took a series of four short lessons in microsurgery: how to reattach tiny vessels. Each lesson included some instruction followed by some practice. Half the docs completed all four lessons in a single day, which is the normal in-service schedule. The others completed the same four lessons but with a week’s interval between them.

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In a test given a month after their last session, those whose lessons had been spaced a week apart outperformed their colleagues in all areas—elapsed time to complete a surgery, number of hand movements, and success at reattaching the severed, pulsating aortas of live rats. The difference in performance between the two groups was impressive. The residents who had taken all four sessions in a single day not only scored lower on all measures, but 16 percent of them damaged the rats’ vessels beyond repair and were unable to complete their surgeries.

Why is spaced practice more effective than massed practice? It appears that embedding new learning in long-term memory requires a process of consolidation, in which memory traces (the brain’s representations of the new learning) are strengthened, given meaning, and connected to prior knowledge—a pro cess that unfolds over hours and may take several days. Rapid fire practice leans on short-term memory. Durable learning, however, requires time for mental rehearsal and the other processes of consolidation. Hence, spaced practice works better. The increased effort required to retrieve the learning after a little forgetting has the effect of retriggering consolidation, further strengthening memory.

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Interleaved Practice

Interleaving the practice of two or more subjects or skills is also a more potent alternative to massed practice, and here’s a quick example of that. Two groups of college students were taught how to find the volumes of four obscure geometric solids (wedge, spheroid, spherical cone, and half cone). One group then worked a set of practice problems that were clustered by problem type (practice four problems for computing the volume of a wedge, then four problems for a spheroid, etc.). The other group worked the same practice problems, but the sequence was mixed (interleaved) rather than clustered by type of problem. Given what we’ve already presented, the results may not surprise you. During practice, the students who worked the problems in clusters (that is, massed) averaged 89 percent correct, compared to only 60 percent for those who worked the problems in a mixed sequence. But in the final test a week later, the students who had practiced solving problems clustered by type averaged only 20 percent correct, while the students whose practice was interleaved averaged 63 percent. The mixing of problem types, which boosted final test per for mance by a remarkable 215 percent, actually impeded performance during initial learning.

Now, suppose you’re a trainer in a company trying to teach employees a complicated new process that involves ten procedures. The typical way of doing this is to train up in procedure 1, repeating it many times until the trainees really seem to have it down cold. Then you go to procedure 2, you do many repetitions of 2, you get that down, and so on. That appears to produce fast learning. What would interleaved practice look like? You practice procedure 1 just a few times, then switch to procedure 4, then switch to 3, then to 7, and so on.

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The learning from interleaved practice feels slower than learning from massed practice. Teachers and students sense the difference. They can see that their grasp of each element is coming more slowly, and the compensating long-term advantage is not apparent to them. As a result, interleaving is unpopular and seldom used. Teachers dislike it because it feels sluggish. Students find it confusing: they’re just starting to get a handle on new material and don’t feel on top of it yet when they are forced to switch. But the research shows unequivocally that mastery and long-term retention are much better if you interleave practice than if you mass it.

Varied Practice

Okay, what about the beanbag study where the kids who did best had never practiced the three-foot toss that the other kids had only practiced?

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The beanbag study focused on mastery of motor skills, but much evidence has shown that the underlying principle applies to cognitive learning as well. The basic idea is that varied practice—like tossing your beanbags into baskets at mixed distances—improves your ability to transfer learning from one situation and apply it successfully to another. You develop a broader understanding of the relationships between different conditions and the movements required to succeed in them; you discern context better and develop a more flexible “movement vocabulary”—different movements for different situations. Whether the scope of variable training (e.g., the two- and four-foot tosses) must encompass the particular task (the three-foot toss) is subject for further study.

The evidence favoring variable training has been supported by recent neuroimaging studies that suggest that different kinds of practice engage different parts of the brain. The learning of motor skills from varied practice, which is more cognitively challenging than massed practice, appears to be consolidated in an area of the brain associated with the more difficult process of learning higher-order motor skills. The learning of motor skills from massed practice, on the other hand, appears to be consolidated in a different area of the brain that is used for learning more cognitively simple and less challenging motor skills. The inference is that learning gained through the less challenging, massed form of practice is encoded in a simpler or comparatively impoverished representation than the learning gained from the varied and more challenging practice which demands more brain power and encodes the learning in a more flexible representation that can be applied more broadly.

These Principles Are Broadly Applicable

College football might seem an incongruous place to look for a learning model, but a conversation with Coach Vince Dooley about the University of Georgia’s practice regime provides an intriguing case.

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Dooley is authoritative on the subject. As head coach of Bulldogs football from 1964–1988, he piled up an astonishing 201 wins with only 77 losses and 10 tied games, winning six conference titles and a national championship. He went on to serve as the university’s athletic director, where he built one of the most impressive athletics programs in the country.

We asked Coach Dooley how players go about mastering all the complexities of the game. His theories of coaching and training revolve around the weekly cycle of one Saturday game to the next. In that short period there’s a lot to learn: studying the opposition’s type of game in the classroom, discussing offensive and defensive strategies for opposing it, taking the discussion onto the playing field, breaking the strategies down to the movements of individual positions and trying them out, knitting the parts into a whole, and then repeating the moves until they run like clockwork.

While all this is going on, the players must also keep their fundamental skills in top form: blocking, tackling, catching the ball, bringing the ball in, carrying the ball. Dooley believes that (1) you have to keep practicing the fundamentals from time to time, forever, so you keep them sharp, otherwise you’re cooked, but (2) you need to change it up in practice because too much repetition is boring. The position coaches work with players individually on specific skills and then on how they’re playing their positions during team practice.

What else? There’s practicing the kicking game. There’s the matter of each player’s mastery of the playbook. And there are the special plays from the team’s repertoire that often make the difference between winning and losing. In Dooley’s narrative, the special plays stand as exemplars of spaced learning: they’re practiced only on Thursdays, so there’s always a week between sessions, and the plays are run in a varied sequence.

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With all this to be done, it’s not surprising that a critical aspect of the team’s success is a very specific daily and weekly schedule that interleaves the elements of individual and team practice. The start of every day’s practice is strictly focused on the fundamentals of each player’s position. Next, players practice in small groups, working on maneuvers involving several positions. These parts are gradually brought together and run as a team. Play is speeded up and slowed down, rehearsed mentally as well as physically. By midweek the team is running the plays in real time, full speed.

“You’re coming at it fast, and you’ve got to react fast,” Dooley said. “But as you get closer to game time, you slow it down again. Now it’s a kind of rehearsal without physical contact. The play basically starts out the same each time, but then what the opponent does changes it. So you’ve got to be able to adjust to that. You start into the motion and say, ‘If they react like this, then this is what you would do.’ You practice adjustments. If you do it enough times in different situations, then you’re able to do it pretty well in whatever comes up on the field.”

How does a player get on top of his playbook? He takes it home and goes over the plays in his mind. He may walk through them. Everything in practice can’t be physically strenuous, Dooley said, or you’d wear yourself out, “so if the play calls for you to step this way and then go the other way, you can rehearse that in your mind, maybe just lean your body as if to go that way. And then if something happens where you have to adjust, you can do that mentally. By reading the playbook, rehearsing it in your mind, maybe taking a step or two to walk through it, you simulate something happening. So that kind of rehearsal is added to what you get in the classroom and on the field.”

The final quarterback meetings are held on Saturday morning, reviewing the game plan and running through it mentally. The offensive coaches can make all the plans they want to about the hypothetical game, but once play gets under way, the execution rests in the hands of the quarterback.

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For Coach Dooley’s team, mastery arrives from a disciplined regimen of spaced, interleaved, and varied practice. The seasoned quarterback going into Saturday’s game— mentally running through the plays, the reactions, the adjustments— is doing the same thing as the seasoned cop preparing to make a traffic stop and the neurosurgeon who’s rehearsing what’s about to unfold in the operating room.

Peter C. Brown is a writer and novelist in St. Paul, Minn.; Henry L. Roediger III and Mark A. McDaniel are professors of psychology at Washington University in St. Louis. This essay is adapted from their book, "Make It Stick: The Science of Successful Learning," published by the Belknap Press of Harvard University Press in April. Copyright © 2014 by Peter C. Brown, Henry L. Roediger III, and Mark A. McDaniel. Used by permission. All rights reserved.