Why is spaced repetition not better known?

Suppose a method let you remember things with a 95% success rate–in other words, whatever information you’ve put into a system, you’d have a 95% chance of recalling it–and this effect is permanent, as long you continue to use the method. That would be quite remarkable, wouldn’t it?

Well, there is such a method, called spaced repetition. This is the method used by such software as Supermemo, Anki, Mnemosyne, and Memrise.

The figure, 95%, is very impressive to me. I’ve been thinking about it lately, as I delve into the world (it is a whole world) of spaced repetition. Ordinarily, we require much less out of our metrics. 95% is practically a guarantee. With just 15 or 30 minutes a day, adding maybe 20 questions per day, you can virtually guarantee that you will remember the answers.

In particular, I am wondering why spaced repetition is not used more widely in education. Of course, I’m not the first to wonder why. The answer is fairly simple, I think.

The more I read from and interact with educationists and even homeschoolers, the more I am struck by the fact that many of them hold knowledge in contempt (q.v.). Of course, they will cry foul if you call them on this (q.v.), but that doesn’t change the fact (q.v.). So naturally I expect them to sneer at me when I express amazement at the 95% recall figure. I can hear the “arguments” already: this is “rote memorization” (not if you understand what you’re memorizing); education is not about amassing mere facts (not just that, no); it suffices that you can just look answers up (wrong); we should be teaching critical thinking, not mere memorization (why not both?).

I am not going to defend the value of declarative knowledge (again) here. I simply wanted to observe what teachers (including homeschooling parents) could do with spaced repetition, if they wanted to. They could spend a half hour (or less) every day adding questions to their students’ “stack” of questions; then assign them to review questions (both new and old) for a half hour.

Imagine that you did that, adding 20 questions per day, five days a week, 36 weeks per year (the usual U.S. school year), for six years. This is not impossible to manage, I gather, and would not take that long, per day. Yet by sixth grade, your students would have 21,600 facts in recall with about 95% accuracy. These would merely be the sorts of facts contained in regular textbooks.

Next, consider an exam that drills on a random selection of 100 of those facts. The students who used spaced repetition faithfully would probably get an A on the exam. That, I suspect, is much better than could be expected even from top students who used ordinary methods of study.

Would students who spent 30 minutes out of every class day on this sort of review benefit from it?

I think the answer is pretty obvious.

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About the author

Larry Sanger had written 160 articles for Larry Sanger Blog

I call myself an "Internet Knowledge Organizer." I started Wikipedia.org, Citizendium.org, WatchKnowLearn.org, ReadingBear.org, and Infobitt. I write about education and the Internet from a broadly philosophical point of view.

14 Responses to "Why is spaced repetition not better known?"
  1. Reply PokerDad May 10, 2012 12:02 pm

    I never knew about it myself until I was studying for a post grad exam a few years back and saw someone mention it on a forum. Until then, I was using antiquated methods. Empirically, I’ll posit a percentage is due to ignorance, meaning the idea doesn’t have a chance to spread. However, the larger question which I believe you might be alluding to, is why the method isn’t used more frequently given the multitudinous information available. It’s a disconcerting notion to think that educators purposely eschew a proven method of learning solely on the basis that it doesn’t comport to their pedagogical theories. I would surmise that these are the two biggest reasons why it isn’t more widely known.

  2. Reply Larry Sanger Blog » An assortment of things that should exist May 11, 2012 10:58 am

    […] A website+app with spaced repetition questions that teach basic facts school students (preK and […]

  3. Reply Bronwyn May 15, 2012 06:28 am

    Actually I have been wondering something similar about the way our young children are often taught the letters (and their sounds) in preschool. Very often this is done by letter of the week and I believe this is not a good way to teach this – it would be better to teach more at a time with plenty of spaced repetition. Naturally the more something is repeated the more it will be remembered and spacing well is needed so that the maximum amount can be presented and remembered.

    However, I would be careful of teaching certain “facts” as much of what we learn could be opinion rather than fact and I would not like to influence my child with “facts” which are not true. I am not even going to put examples of this here – I am sure everyone can think up their own versions or even think of things they themselves have had to relearn due to opinions changing.

    • Reply Larry Sanger May 15, 2012 08:23 am

      Agreed re learning ABCs–although e.g. my 19-month-old is learning his ABCs, and I wouldn’t use this method with him, because the method requires testing and it is a bad idea to test little ones.

      Re teaching facts, well, you do your best. You have to start sometime. I suspect the word “fact” is what you’re reacting to. Well, call them purported facts. We can’t do better than what we ascertain to be facts after conscientious research and formulation. If we don’t teach that, then we don’t teach any declarative knowledge at all, leaving children in ignorance. If it comes down to ignorance vs. a large belief system that is 98% accurate, I’ll go with the latter.

  4. Reply LittleFish May 31, 2012 18:28 pm

    I have been using Supermemo for the past six years, and I have more than 50,000 flashcards in my database. Supermemo has been in development since 1982, and it has the longest track record of any such programs. I keep in contact with the creator, Piotr Wozniak and keep a (semi-regularly updated) blog about different things I encounter in using Supermemo in my life.

    Spaced Repetition is the key to long-term knowledge retention, and it would benefit the world greatly if it were used in a more widespread manner. Why will it not likely get more popular?

    -The benefits are not immediately discernible; we live in an environment that encourages and favors short-term benefits and instant gratification. (“If exercise were a pill, it would be the most prescribed of them all.”)

    -Self discipline is required to use such a program every day, without skipping. I have done this for the past six years (Even if that meant doing it on a bus late at night when I forgot). Self-discipline is not encouraged or taught in schools, as teaching self-discipline doesn’t bring immediate “stats” up (Test scores, dropout rate, etc.).

    -Our society is obsessed with various statistics that are supposed to measure knowledge retention simply because that was the only way we could measure them in the past. Spaced Repetition is part of a superior learning methodology that isn’t as easy and profitable to pursue in the short term. Until the structure of school is no longer CPD (Cram, pass, then dump the information), Spaced Repetition will only be used by obsessive and self-motivated autodidacts.

    I have a very pessimistic view of groups of people, specifically institutions. While it is good to learn things, the institution of education (At least in the United States) is bogged down by too many problems (Antiquated teaching methodology, money, etc.), I highly doubt Spaced Repetition will be adopted in any large way.

    • Reply Larry Sanger May 31, 2012 19:30 pm

      What a depressing point of view! You might be right, but I wonder if, combined with the right interface/software, it might have a better chance of catching on…

      • Reply LittleFish June 1, 2012 06:55 am

        Obviously if it were done in a more user-friendly way and adopted/implemented by a large company, it would get in front of more people’s eyes. If Google bought Supermemo or Apple had a Spaced Repetition App automatically installed on all iPhones and iPads, people might pay attention more. But I consider it like a rare and (right now) incurable disease. Unless someone of note (Movie star, sports athlete, etc.) has it, money is less likely to be allocated to find a cure. Unless a large company forces a lot of people to look into it, it won’t go beyond the small lot of enthusiasts that use it now.

        I want to be more optimistic about the future, but society always finds a way of disappointing me to a greater and greater degree, exceeding my most pessimistic expectations. While technology innovations have done much to aid in education, communication, etc., we’re just keeping our minds off of the negative core problems that are only getting worse (Inequality, injustice, unpunished atrocities of cult religions, etc.)

      • Reply devon June 27, 2012 04:26 am

        “You might be right, but I wonder if, combined with the right interface/software, it might have a better chance of catching on”. This is what I think and what we are trying to do.

        I got to know spaced repetition when I search flashcards app. Someone already is a ‘self discipline’ people when he wants to use flashcards. But most of us are not.

        We made our first app for this purpose. It’s called Memonote. Users do not need to know the term ‘Spaced Repetition’. We just jot down what we want to remember into a note system, sync to iPhone/iPad, use reminder/clock for daily review.

        It works great for myself. I already have more than 300 notes in last month and I remember them very well. I wrote down every item I want to remember from PDF, web pages, reading…

        1) Easy note taking, 2) Sync to mobile device, 3) Reminder for daily review. There are key featurs for my solution.

  5. Reply Larry Sanger Blog » Memory method July 8, 2012 23:18 pm

    […] Memory method Print PDF (The following is edited and elaborated from my comments in┬áthis BrillKids Forum discussion. The BrillKids Forum is awesome. The method we follow is greatly updated in this post.) […]

  6. Reply Katharine Birbalsingh April 6, 2014 14:46 pm

    Hi Larry – I’m from the FB group. I discovered EL thanks to you. Where do you live? I think you’d be really interested in this book coming out on 28 April, called Progressively Worse, written by a friend of mine. It is about progressive education and why the UK is as bad as it is, but he also talks somewhat about the US and all the policies are pretty much the same between the two countries anyway. You’d love it. What do you think of ED Hirsch? Do you know of him? Best wishes Katharine

    • Reply Larry Sanger April 6, 2014 21:48 pm

      Hi Katharine, it’s strange but excellent to be the one to introduce EL to anybody! I’d love to see the book and will be on the lookout for it.

      I’ve read a couple of Hirsch’s books and am a fan.

  7. Reply Katharine Birbalsingh April 7, 2014 03:49 am

    Hi Larry
    Can you email me? I’d really like to talk to you about these memory systems. I’m a teacher and we are building an IT system to do something similar to the systems you are talking about so that we can get children to remember what we teach them. I want to ask you about the details of these systems and doing this via comments on a blog post is difficult. If you can email me, then maybe we could have a discussion. I realise you must be very busy. I don’t want to take much of your time. You will find what we are doing as a school very interesting so I promise you will enjoy talking to me! Have you read Dan Willingham’s Why students don’t like school? You’d like it, I’m sure.

    • Reply Larry Sanger April 7, 2014 11:28 am

      No problem. I would be absolutely fascinated to see spaced repetition used in classrooms.

      Yep, read the Willingham book.

  8. Reply Olya April 12, 2014 21:15 pm

    My husband learned to speed read when he was in college (about 20 years ago). It took him only one month. He reads 900 words a minute. He was so amazed by the results at that time that he went to his high school principal to tell him about the course/program, and I believe he offered to teach it to the high school kids. He was shocked when the response was – thank you but we are not interested. It seems like a lot of people don’t care about what is true and what is right. Another example, my husband’s main interest and passion has always been epistemology. Years and years ago he figured out the answer to the main question of epistemology. He went to talk to a philosophy professor at University of Virginia, but the professor wouldn’t even listen to him. His answer, basically, was – who do you think you are? It is sad. It is also great to have people like you who push good ideas through the mass of ignorance. Thank you.

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