Finishing a 2000 word course by learning 100 words per day

This spaced repetition made me really curious about the math in learning a course on Memrise.

I’m not sure if these numbers are outdated for spaced repetition:
After you learned a word, it will occur again in 4 hours. When you got it right after 4 hours, it will occur again in 12 hours, and then in 1 day, 6 days, etc. I’ll just list the whole thing.

4 hours
12 hours
1 day
6 days
12 days
24 days
48 days
96 days
180 days
180 days
180 days

It seems 180 days is the cap for Memrise’s spaced repetition.

Assuming these numbers are still applicable and my calculations are correct, for a 2000-word course and learning 100 words a day, and let’s say you start learning the course on January 1st. You’ll also learn the course every day [including Saturdays and Sundays without any flaws and the timing is perfect that is to say you review the words immediately when it’s time to review and more importantly, you review all the words needed to be reviewed]. You’ll finish the course on January 21st. Also on the first days, you’ll be learning twice or thrice as much work at the beginning of the month [circa January 2nd to January 27].

From January 2nd to January 27, it’s expected that you will be having 200-300 words to review every day. After January 27, it’ll drop to 100 words per day until February 8th. The highest amount of words to review in a day is 400 and that day would be January 20th. It’s the only day that you’ll be getting 400 words to review.

Then you’ll have a 4-day break from February 9th to February 12th. Reviewing starts again on February 13th and ends on March 4th. It’s expected that you have an average of 100 words to review every day in this session.

After March 4th, you’ll have a break of 28 days, and reviewing starts again on April 2nd and ends on April 21st. The average words to review per day is 100.

After that you’ll have a break for 76 days!

Next reviewing session is on July 7th to July 26th. The average words to review per day is still 100.

And then another break for 160 days. Does this remind you that you’re reaching for your 180-day spaced repetition? Well, in the next session of reviewing, you’ll be finally achieving your 180-day gap.

Ok, the next session is going to be on January 3rd the next year and ends on January 22nd. Still, the average words to review is 100. And after the session, you’ll be having another 160-day hiatus.

And the next 180-day gap starts on July 2nd the next year.

I estimate the points you’ll be collecting in this very long span of time would be 3,300,000 in this single 2000-word course from January 1st to July 21st the next year.

How did I get these numbers? I used a calendar and wrote numbers on them and added them. Haha. Also, a good calendar is the year 2017 because January 2017 starts on a Sunday. But I hope my analysis and computation is correct. I might have got some errors in the way.

Anyways, thanks for reading this bizarre and nerdy post, and have a nice day.


Yes it depends if you correctly match each word exactly. But we are humans. Plus there’s some variation when and what time you do the tests. Some of us don’t use Memrise every day (well I do…).

Hi @ekoi1995,

I think Pelden makes a good point. I think your figures assume a zero error rate, which is unlikely in practice.

From my own experience (and I’m probably a below average learner), learning 10 new words per day while keeping the review box under control involves spending about 35 minutes per day (after reaching steady state).

So in reality, learning 100 words per day might well end up as a ~6 hour per day project - probably a quite painful schedule for most people.

I can only add that there do have to be some flaws in Memrise’s application of the SRS. I’ve also thought about the whole system, but didn’t bother to do any math (got other things to do! :slight_smile: ).

For instance, I’m working on a 5k words course where I have learned 3879 of 4524 words (~85%; I’ve ignored many words). I have been working on this course for at least 2,5y, I don’t think I ever missed a day (Memrise removed my streak twice during that time, so I don’t know exactly)
I rarely learn less than 3 words per day, sometimes up to 20. I review all words up for review every day with very few exceptions. I should thus get a very large number of words, each and every day. But I don’t. Some days I get like 20, some days 120 and everything in between. Sometimes I even get none (in which case I seem to get twice the somewhat regular amount the day after). It’s chaos really. This applies to other courses (with many words) as well, BTW.

Yes, the algorithm is dependent on both it’s period settings and what you do, and we humans do not operate like computers, the periods between and words learned or miss variates all the time.

I did notice the spaced repetition for the wrong answers is different. And as I tried observing it, it will occur again in 7 days. I haven’t observed the next number when I get it right again in 7 days. [Out of curiosity, I will check it.] Also when I get a review word wrong, it will occur again in 13 hours. And I guess when I get it correct, it’ll occur in 7 days.

I see a pattern. In the original list:
4 hours
12 hours
6 days
12 days

The wrong words I currently observed are 1 number greater than the original.
13 hours - 1 hour = 12 hours which we can see in the original list.
and 7 days - 1 day = 6 days which we can also see in the original list.

So I assume, when I get the word right in 7 days, I really guess it’s going to be 13 days.

With that, I guess it follows the same pattern of increasing gaps. Just only 1.17% longer than the original.

And yeah, getting review words wrong just derails it out of schedule. And it just shifts to one day in the calendar (well making it noticeable from other sessions).

But if you’re accuracy in reviewing sessions is 95-99% (100 words per session) [Well I always do.] Those confusing words are just those 1-10 words for reviewing every 13 hours [yeah I always get them wrong because they’re so confusing]

I think the spaced repetition is kinda hardcore. XD
I prefer learning words at 7:00 AM and then on the same day, the review starts at 11:AM 1 hour before lunch which is favorable. But then the 12 hours ruined it. I need to stay up late to review at 11:00 PM. I always believe I’ll forget the words if I don’t review them. And also the following +6 days and +12 days will always concentrate on the 11 PM. So if I learn new words every day at the same hour at 7:00 AM, my default reviewing time is 11 PM. I guess I need to change the time of learning new words. [And I can’t learn words at any hour because, yeah, work. :smile: ]

And yeah I see, the chaos on the popping out of words to review is really normal if you learn words in different hours. For example, learning new words on day 1 at 7 AM and on the Day 2 at 8AM, could already have an unpredictable outcome. XD

But if you try to learn new words in a very specific hour of day everyday, you’ll have a default reviewing time which is always 16 hours from there.

Hi! and Yep. I like to think it as the greatest possible outcome and if anything gets greater than that I guess it’s a hack X’D.

Oh I see! That’s nice. I can learn 20 words in 0.75 to 1.5 hours. Well, yeah longer for languages that are really different from Latin and Romance Languages. I’m really much faster learning languages related to Latin.

And also, I can review 100 words in 5-10 minutes. I usually get 500 words to review and could take me an hour or two to review them all in one go.

Also if you do Classical review of any existing words and you fail, they are added in to the algorithm to be learned later so that also mixes up the word frequency.

I agree with that, it looks like quite a lot of words get ‘swllowed’ by the system and don’t come back after 180 days, or only occasionally, or after much longer when it finds them again.
I don’t think I could revise/water everything otherwise, give the number of words/expressions I’ve added over the years

@mthierst @Olaf.Rabbachin

There is a bug for occasional words, which affects 1 item per about 5-6 thousand (see this thread), but otherwise as far as I can see repetition algorythm works OK. I’m classically reviewing a big number of courses once a year, and it’s easy to see how they reappearing in they same order as they were reviewed 6 months ago.

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Oof. That sounds like the word isn’t worth reviewing anymore and Memrise thinks it’s already implanted in your brain. X’D Just kidding.

But wow. I never encountered a glitch like that yet.

I can add that I often (probably like once a week) get a number of items to review and, after having done that, new words (1-3) appear one to three times. That can’t be right and looks like a classic indicator for a bug.

interesting - it’s not how it feels, but maybe you are indeed correct. 18k words would amount to 100/day average as a minimum repetition (assuming all correct, and evenly distributed), so maybe I’m seeing all entries I’ve learned indeed.

I’m trying to avoid bulk-handling multiple courses in a row, and space them out over the day, at least his way there’s a spread. Long term it will be minimized anyway as we humans remember some words and forget others.

PS: A refinement to the algorithm for long term words would be to randomize the spread of the next date/time +/- one day or something similar.

It took me about 27 days to learn 2,788 words in Croatian. I spent 4 or more hours every day learning and reviewing and so far have focused only on speed reviews, leaving traditional reviews for later once I start getting every single word in my speed reviews correct. I would say after these 27 days about a third to a half are in my working vocab and the rest are passive or barely memorized (can only pick them out of a speed review and probably wouldnt recognize them while reading unless the context was very clear). You can definitely introduce yourself to 100 words a day but it will be many many more days after you finish the course before you’ve internalized them.


I did an experiment with a couple of items in two different community courses, and this is what I get in repetition cycles for both of them:

1, 2, 3, 10, 23 + 17

Eхplanation: I’ve learned them on December 1st, today is January 17th. Intervals are 0 + 1 + 1 + 7 + 13/14? + 25 days. I’m doing learning sessions once a day, thus I’ve had first sessions for three days in a row. The next time I’ll review them in 48 days, though I’m not sure if I will not break a streak until then.

I don’t know if it proves your theory or not, but at least they were appearing for reviews in accordance with some system. :slight_smile:

P.S. Does it correspond with declared cycle?

I suppose don’t understand what you’re trying to convey. :slight_smile:

But yes, of course there is a system. The problem being that, at some point, the system seems to be erroneous. Otherwise you wouldn’t get new words up for review in the pattern I posted. I might not have been clear enough. Here’s an example of what happens at least once a week here:

  1. Memrise shows that you have 40 words up for review. You do a session with these 40 words
  2. Right after having finished, Memrise tells you that you have 3 words up for review. You do a session with these 3 words
  3. Right after having finished, Memrise tells you that you have 2 words up for review. You do a session with these 2 words
  4. Right after having finished, Memrise tells you that you have 1 word up for review. You do a session with that one word
  5. Memrise tells you that you have no further words up for review.

There might be occasions when one of the last two above (3./4.) doesn’t come forward. But that’s how it usually goes.

My experiment was in vain. :slight_smile:

Though I saw this pattern, too, and I can guess about its origins. I think problem lies in fact that items are appearing for reviews in round cycles, which are 24 hours, 48 hours, etc. Thus if you are doing your sessions at more or less the same time, it’s logical for items to reappear with delay.

For example, you start your session at 12.00 and make a review of a certain word at 12.15. It means that it will reappear at 12.15 some days after, and after several sessions your time of its review can be shifted to 12.20 or 12.25, and there’ll come a day when it appear for review after your usual session is already over.

For this system to be perfect review cycles should not be round, for instance, it could be 23 hours and 30 minutes, or 6 days, 23 hours and 15 minutes, so that items will appear before your session, not during or after it.