When Will Schools Space, Interleave, and Vary Practice?

If school’s purpose were to develop skills, we’d teach differently:

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. … [But] the benefits of spacing out practice sessions are long established. …

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. …

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. (more)

So, a good test of a theory of school is: how long do you predict it will take teachers to learn this lesson? The article above talks about how many coaches have learned this lesson, plausibly because they really do want to win games, and face strong competitive pressures.

If you think the main function of schools is something other than learning, you might think it could take a very long time before schools adopt these practices. If you think the main function of schools is learning, but that public schools face much weaker pressures to be efficient that private schools, you might predict that private schools will adopt this much faster. If you think public schools are effective at adopting better approaches, you might predict that they adopt these quickly. So, what do you predict?

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  • joshsacks

    Source article sounds interesting. Can we get a link?

    • http://overcomingbias.com RobinHanson

      Oops; fixed.

  • Paul Gowder

    The problem is that there are countervailing considerations. For example: last year I needed the capacity to make sense of Attic Greek, and I needed it fast. So I went off and took an intensive summer course. Was that the best way to learn the language? Has as much stuck as I’d like? No, and no. But I needed it in the near term, and short-term efficiency won. I suspect these considerations drive a lot of the massed practice.

    • http://rs.io adbge

      More generally, that sounds like a consequence of hyperbolic discounting.

      gwern’s excellent article has this to say:

      Across experiments, spacing was more effective than massing for 90% of the participants, yet after the first study session, 72% of the participants believed that massing had been more effective than spacing….When they do consider spacing, they often exhibit the illusion that massed study is more effective than spaced study, even when the reverse is true (Dunlosky & Nelson, 1994; Kornell & Bjork, 2008a; Simon & Bjork, 2001; Zechmeister & Shaughnessy, 1980).

      • Paul Gowder

        Or just a consequence of rational time management. If a learner needs knowledge a lot now, and anticipates needing it only a little bit later, it’s perfectly rational to invest in fast but long-term ineffective learning strategies.

        (This is why cramming for exams can also be perfectly rational, for a student who is only interested in the grade, and doesn’t give a fig if the knowledge sticks around long-term. If the student crams for the final she can use the time saved earlier in the semester to invest in other things.)

    • http://juridicalcoherence.blogspot.com/ Stephen Diamond

      I suspect those considerations drive mass practice as rarely as your personal example suggests.

      [As for students being “rational” by cramming, the problem is the academic system that encourages it. Regarding whether it is individually rational, see The Hidden Meaning of “Memorization” among Exam Abolitionistshttp://tinyurl.com/39oecbp .]


    Isn’t interleaving already practiced? Isn’t teaching different subjects during the week already a form of interleaving? There does seem to be a great deal of variety between countries and institutions. Btw I do not think public schools (I assume you mean secondary education) can choose their teaching methods, nor can private schools that are part of a large organization (such as catholic schools). You would have to look at universities and private colleges, though of course on a national scale public institutions can choose different methods (German methods of course differ from American methods).

    “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.”

    Is this always the goal or even useful compared to the disadvantages? I can imagine some subjects (math, physics) are so difficult that the first priority is to get students to understand them, before even thinking of applying those skills to something else, in those cases retention isn’t as much an issue either so interleaved teaching might be worse. medical school does sound like a place where interleaved teaching would be very useful, but I know of universities that teach it without any interleaving at all (not even teaching different subjects during the week).


    P.S. There is not one goal of schools and colleges/universities. They exist because a lot of different people want them to exist for different reasons but they agreed on the concept of learning institutions themselves and therefore struck a deal. And that was just in the beginning, later other groups exerted influence over the whole system as well and now there’s definitely not a single vision behind the concept of a school, and that’s true for most countries.

  • http://greyenlightenment.com/ (new site) Economics Institute

    Spacing is more effective from personal experience

  • BJ Terry

    One major problem is that it’s simply impossible to learn, long-term, the amount of stuff that schools have promised society that they will teach. Massed practice allows them to pretend that they’ve taught all the things in this massive curriculum, without holding themselves accountable to actual retention after a year or two.

    You can force students in a few weeks to learn items to a depth of (say) 10 and then test them on it, and they will pass at that depth, but later they will only remember it to a depth of 2. If you instead interleave studying, they may only ever get to a depth of 6 for the final testing at the end of the school year, but will have long-term retention to a depth of 4. Clearly the interleaved learning is better for their knowledge over their lives, but then you can’t support the fiction that you’ve taught and tested them on depth 7-10.

    • IMASBA

      Then again you might be fine with most students just retaining level 2 but some having had the opportunity to be introduced to level 10 and choosing to study that further…

  • arch1

    I wish the article had been clearer on the scale of the interleaving. At a coarse scale, most schools seem to interleave; while at a fine scale (say 15 mins), interleaving seems much less prevalent. (Which might in part answer IMASBA’s 2nd Q below)

  • stobiepole

    I think higher education is more or less modelled on the priesthood, and while the particular articles of faith are important, what is really being taught and assessed is an ability to conform and a dedication to maintaining the interests of the priesthood and associated institutions. At least that’s my experience…

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  • http://overcomingbias.com RobinHanson

    The post asked a direct prediction question, and twelve comments later, still no one rises to the bait?

    • Robert Koslover

      I predict that neither public nor private schools will change their practices significantly. After all, almost no one actually cares about claimed results of research in teaching and education — and why should they, when there is so very much nonsense in that field, effectively burying/hiding anything that might be of actual value? Instead, the relabeling, recycling, and rediscovery of old approaches, but treating them as if they were novel, will continue unabated. Expensive, large, and extravagant conferences on education and teaching will continue to be held, will be enjoyed by many as a reward for their otherwise dreary jobs, and will achieve little. Meanwhile, the greatest quantities of effective education will arise from variously the dedicated efforts of handfuls of parents, handfuls of good teachers, and handfuls of well-motivated students.

    • IMASBA

      You have to define interleaving more clearly, as arch1 and I have said.

    • http://juridicalcoherence.blogspot.com/ Stephen Diamond

      My speculation would be that within five years, some elite school(s) will have incorporated interleaving practices. It won’t be adopted for mass education for the (perhaps good) reason that it reduces motivation, which is a scarcer resource than time for most students.

  • Quixote

    Non magnet public schools will make no changes. Test prep companies will adopt this. Some pirate schools will adopt this, but most will not. Learning is relative and if they produce more of it than public schools the market won’t reward them for winning by a bigger margin.

    • B_For_Bandana

      It’s my understanding that the majority of your quality pirate schools already interleave practice between swigging rum, burying treasure and forcing mutineers to walk the plank.

    • http://overcomingbias.com RobinHanson

      Pirate schools? Why aren’t kids begging their parents to go there? 😉

      • Peter David Jones

        Some say they’re strong on the three Aaarrrs…whilst others maintain they just teach kids to parrot.

  • Jordan Fisher

    This is how I taught when I was still in academia. The students didn’t terribly appreciate it, but I like to think they did learn more. I’m not sure this is nefarious on the parts of teachers/institutions, so much as momentum, tradition, and a lack of desire to innovate.

  • B_For_Bandana

    I teach math at a public high school. We have a practice that is sort of like this, called “spiral reviewing.” A teacher who uses spiral reviewing a lot still uses an old-fashioned course sequence where topics are covered intensively, one at a time. But for a few minutes every day in class, and (sometimes) even on graded assessments, they have the students do problems on old topics. Over a school year, each topic gets circled back to maybe 5-10 times, after being covered intensively the first time.

    Spiral reviewing is not stressed very much by administration, and there are no penalties or anything if you don’t spiral. It’s just mentioned every so often as a good idea, and most of the better teachers (at least in math, not sure about other departments) do it. I’m new this year, and I’ve always felt rushed and ill-prepared, so I have not done spiral review myself. But it is something I aspire to do next year, when hopefully I’ll be more prepared and experienced.

    So optimistically, this is halfway between massed and interleaved practice. If we see the benefit of spiraling, then an optimistic prediction is that practice will get more interleaved as time goes on. Pessimistically, it’s a fad that will go away soon. Not sure which is more plausible.

  • Jayson Virissimo

    I think the main function of schools is something other than learning, so I predict that “the majority of public schools in Arizona will not require students to utilize spaced repetition software at any point within the next 10 years.”


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  • Alice Swan

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