Hacking Chinese

A better way of learning Mandarin

Spaced repetition software and why you should use it

Spaced repetition means that you review words you want to learn at certain intervals to maximise learning efficiency. It is a well known psychological phenomenon that repetition is much more efficient when spread out instead of massed together. Since this involves keeping track of much data, a computer program is needed to handle it properly. In this article, I’m going to argue that spaced repetition software is the best thing since sliced bread and that it’s a must in the long run for any serious learner.

At the moment, I’ve studied >20 000 Chinese words and if you gave me a test on all of them, I would score 90-95%

More amazing still, I only spend about 30 minutes a day maintaining vocabulary. I don’t say this to boast, I say this because I know for a fact that you can, too, if you just use the proper tools. I say this because it illustrates how powerful spaced repetition can be. Please follow  along and see why you should start using spaced repetition software today if you aren’t already doing it!

Learning languages is different from learning many other subjects in that almost everything we learn are built on something we already know. At beginner and intermediate levels, we can never study an area and, when we’re done, just leave it. We need to learn and we need to remember what we learn even after the exam. This is perhaps true for all subjects, but it’s crucial when learning languages. Is it possible to remember every word you’ve ever studied? Of course it is! It isn’t even hard.

The problem: Reviewing everything takes too much time

With a traditional approach, it would probably be impossible for us to remember almost every word we’ve studied. To do that, you would constantly have to go back and review chapters you’ve studied before, but as the number of chapters grows larger and larger, this would become a hopeless task. Then think of all the words you’ve learnt, but that aren’t in ordinary textbooks.

Reviewing old chapters and vocabulary lists, you waste a lot of time studying words you already know and don’t need to review, just to find those few words you actually needed to revise. This is what makes the traditional approach useless when you move beyond the beginner level.

The solution: Spaced repetition software

Spaced repetition software takes care of this. Each word is assigned an interval, starting at zero. This means that the time remaining until you should review this word is zero, i.e. you should do it now. The program will then give you the word as a flashcard question and if you can answer it correctly, the interval will be increased. The more times you answer correctly, the longer the interval until next time you have to review the word. Thus, words you know well and don’t forget will quickly be assigned very long intervals (months, years), so you won’t be bothered by them and can instead focus on words you find hard.

These intervals aren’t random! In most programs (see below), they are based on research done on vocabulary acquisition, so this will make learning even more efficient.

The point is of course that words you don’t know, i.e. flashcards you answer incorrectly, will have their intervals shortened, probably down to zero again. In effect, this means that you’ve forgotten the word and need to learn it again. You will see the words you’re having problems with all the time, which allows you to learn them properly.

For a simulation of the difference between traditional and spaced review, check this animation:

Spaced repetition software allows you to study the words you really need to study and stop wasting time reviewing what you already know

This saves a huge amount of time. In fact, it saves so much time that something that would otherwise be impossible (such as reviewing everything you’ve ever studied) becomes possible. As I said above, I have more than 20 000 characters and words altogether. Yet, looking at the statistics from the program I’m using, I spend on average only 30-40 minutes every day reviewing vocabulary! For a student with average mental faculties, this would be utterly impossible to achieve without the help of spaced repetition software. With this tool at your disposal and some determination and staying power, it’s not difficult to achieve.

Of course, if you’re a beginner or intermediate students, your deck will be much, much smaller. You will still need to practise more for each word, but at least you will make sure you’re not forgetting what you’ve learnt so far.

What to do next

If you’ve followed the above argument, you should be eager to install some kind of spaced repetition software. There are many of these and I’m not going to start a detailed discussion about their merits and flaws, but in my opinion, a program called Anki is the best choice and it’s also free. It allows you to do everything I’ve said here and much, much more. You can also use it for other subjects (other languages, geography, law, whatever). It also provides a web version you can use to synchronise your flashcard on different computers or smart phones.

Anki, the best of spaced repetition software (my article about the program)
Anki, friendly, intelligent flashcards
(official website)

In addition, there are a variety of other programs out there and I’m simply going to list them so you can try them out if you want to:

Mnemosyne (free)
Pleco (commercial, but partly free)
(commercial, but has free sections)
Skritter (commercial, but with free trial)

Of these, Pleco and Skritter are developed specifically for Chinese. Skritter is the only alternative that focuses mainly on handwriting.

A word of warning

Even though spaced repetition software is very useful, it’s not a panacea. You won’t reach a high level of proficiency by focusing only on relatively isolated parts of a language. Reading and listening is important to learn how words are used, and writing and speaking are necessary if you hope to use these words yourself!

More about spaced repetition on Hacking Chinese

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  1. Linh Tang says:

    I just found out about Hacking Chinese today and I’ll start using Anki. I’ll keep everything posted so that we can study all together.

  2. Albert says:

    This sounds interesting. Where do you get the word lists? Do you just add every word yourself? Is there a way to import words from CC-CEDICT or anything like that?

    1. Olle Linge says:

      I’ve added most of my lists manually, but if you use Anki, there are tons of shared decks that can be downloaded (everything is free). The import function is also quite versatile and it should be possible to modify most lists to a recognised format.

  3. Adrian says:

    What do you put on the flashcards?

    eg. pinyin and english, you have to remember the character?

    eg. the character, you have to remember the pinyin and english?

  4. Olle Linge says:


    I have two kinds of flashcards. Firs,t I have around 3500 that I want to be able write, so for these I go from pronunciation on one side to character and meaning on the other (if I can’t figure out which character it is because there are many with the same pronunciation, I peek at the definition).

    All other flashcards are from characters on one side to pronunciation and definition on the other side. I put an emphasis on this because I think recognition is more useful than recall if the time it takes to learn is included in the equation. See this article about my view on vocabulary.

  5. Dylan says:

    Hi Olle,

    I’d be interested in knowing how you decided on which 3500 characters you needed to be able to write and why the number 3500? I ask this because I’d also like to save myself some time in review from trying to memorize how to write every character I encounter…forever (especially if you use SRS) but at the same time I don’t want to be lazy and limit myself.

    So I guess my next implicit question is, do you have any advise on putting together a list of need-to-know-how-to-write characters?

    1. Olle Linge says:

      I think I said 3500 words, not characters, which makes a huge difference. 3500 is the number of words that appear in the textbook series I used (Practical Audio-Visual Chinese), so at the time it seemed reasonable to know how to write these characters. It’s not really arbitrary because the authors have tried to choose words that are useful. However, that’s no guarantee that they are the best 3500 words to be able to write, of course.

      There are two ways of approaching the problem. Either you could try to construct lists (based on textbooks, HSK lists or whatever) or you could just write Chinese regularly and see which words you really know how to write. If you’re not planning to teach Chinese in the near future, I think the second approach is superior. I can of course write more than the 3500 words I check using Anki, because at a certain level, learning to write new characters simply becomes a matter of using proper mnemonics.

  6. Victor Berrjod says:

    The Goldlist Method ( http://huliganov.tv/goldlist-eu/ ) is an alternative approach, built on the same principles as SRS. I’d say the difference lies in that the Goldlist is a more leisurely approach that incorporates handwriting rather than chaining you to a computer. Now, most people nowadays will be sitting on their computer anyway.

    I have personally had a lot of success with the Goldlist, so I encourage everyone to check it out. SRS is good too, so just go with what you prefer. I feel a little stressed out by SRS’es, personally.

    1. Olle Linge says:

      Look interesting, but I just simply can’t get myself to read that much text without a quick explaaniton of what’s going on first. It sounds too much like someone’s trying to sell the panacea of all language problems and that makes me very, very skeptical. Do you know of a better description of the method? Also, I got a fairly bad impression from the start. I’m using mnemonics and standard SRS myself and some of the mneomnics I made up four years ago are still present in my mind. This is extremely useful for writing characters. So if someone says sthat this always fails, and I can immediately point to one example where it does not, I tend to read the rest in an even more skeptical frame of mind.

  7. Allan Ngo says:

    Hi Olle,

    Great post on SRS. This is indeed a lifesaver compared to using the traditional approach. Let me tell you why 🙂

    During my time studying in China, I kept a separate notebook (other than the one for formal lessons) of all the vocabulary that I chanced upon either through the classroom discussion and conversations that are not part of the formal lessons. These are the sort of words that I tend to use in English that I couldn’t really find in books or dictionaries.

    I cherish this notebook because these are the words that I believe contains the most useful words that I typically will use in conversation. But, not being part of any of my subjects, I often (shamefully) overlook putting the time in reviewing them even if I know I could use them in my daily conversation.

    It’s because the sheer amount of pages I would need to go through did overwhelm me and the traditional approach of studying it seems so cumbersome. So I put it off for “someday”.

    That changed with Anki.

    I manually (there could be a better way) wrote these vocabularies in the system for review. Then wow! I really got into it and made it part of my habit. I am stoked to do it daily because these are the words I actually LIKE to learn. I usually insert a sample sentence as well to remember the context and the reason for which I wrote that word down in the first place.

    It is really a MUCH better way of getting through words I have encountered previously and improve retention. It also gives me an idea of which words I do find difficulty in memorizing. For which I tend to use image association with either the word or the pinyin.

    I would like to look into your mnemonic methodology as well. I used to do that with some of my law subjects before.

    Again, thanks for sharing this post!

  8. jake says:


    I just wanted to point out that the flashcard app from trainchinese also uses spaced spaced repetition where learned cards will sleep and then wake up at varying intervals to test the user. We’d love to know what you think! http://bit.ly/KgFtN2 iOS http://bit.ly/IV9Auw Android http://bit.ly/KBBRLc Blackberry



  9. Mr b says:

    Perosnally I very very rarely forget how to read a word/character I’ve already studied, however remember how to write them is my problem, so the programs Anki feels useless in that regard. I know there is one nice page on internet called skritter, (www.skritter.com), where your also able to practice writing the stroke order. However my writing memory is in my hand, moving my finger on a touchpad doesn’t help me. So I’m still on the traditional learning method.

    1. Olle Linge says:

      I don’t agree that SRS is useless in this case. In fact, I’m pretty sure it works very well. Of course, Anki is not specifically made to correct your handwriting, so you’d have to check yourself if you’re correct or not. However, the scheduling principle behind Anki should work very well for handwriting.

  10. Kevin Lewis says:

    Gotta get some related software like this for my computer lab in my school. Thanks for the article!

    1. Olle Linge says:

      These programs work best when they are used daily by the students. I wrote a term paper a while back about integrating Anki into normal classroom practice and it turned out to be very hard. It was difficult to convince the students to use the software at home. If used in class, it won’t be very powerful because too much time will elapse between sessions. It might work if you have class every day, though. If you try to help students using Anki, I’d be very interested in hearing about the results!

  11. Michael says:

    I’m a hardcore user of Anki as well. I enjoyed reading your article. However, I disagree with your point of view regarding the limitations of the effects Anki will have on overall proficiency. You mentioned retaining over 20,000 vocabularies as in single vocab—using single vocab as cards. This is a common mistake by many learners, especially once they’ve grasped a low level/basic foundation. By spending an enormous amount of time (cumulative) on reviewing individual vocabulary, you could have possibly gained a much higher proficiency level while improving your speaking and listening at the same time. (I’ll explain why further down) There is a much more effective and efficient way to use the software. Once there is some basic foundation of vocabulary, a learner should start learning/acquiring through context–larger parts. A simple fragment or whole sentence containing the target vocabulary word/phrase a learner is burning to learn will suffice. Starting out is tedious, but your reading speed will grow exponentially. In the time it likely takes you to read 200 ‘vocab’ cards, I will have likely read through enough sentences/fragments equaling 1000+ in vocab. Reading in context reinforces basic vocabulary, learned vocabulary, sentence structure, tone-changes(fluidity). This reinforcement is important, because when you read, you also hear it whether it’s silent in your head or aloud—you will become familiar the sentence structure naturally. This will help your listening ability, because you will hear the same or similar sentence structures and not suffer knowing only vocabulary while failing to know how it’s used in context and being unfamiliar with words that typically appear in similar context. By only reviewing single vocabulary cards, you are forcing your brain to ‘work’ slightly harder. Why? Because, your brain will either recognize it right away or it will enter a process of searching for the meaning (recalling it), which may then lead to searching for the context in which the card was added. If that vocab card was imported from some stranger’s deck, then your brain will start searching where you’ve seen it (if you’ve even seen it) among everything you might have come across in Chinese previously. This process is very short, however after a lengthy review session or sessions, you will have exhausted your brain to a greater degree, you will have failed to reinforce context, the words around the target vocab, and overall sentence structure. Your reading speed will remain forever slower than it could be. Also, how many people do you know can tell you what a vocab word means, but then are unable to produce it in context or even understand how it’s used in other context? Or, can’t even manage to produce the basic sentence structure as a template for the vocabulary being attempted? Learning higher level vocabulary requires reading (unless it’s totally possible to constantly have contact with high level (all levels) of vocabulary through listening). Everyday conversations on limited topics can definitely be learned by speaking and listening alone. Now, by using context in cards, let’s say you have added a sentence or fragment. You read through it, hit your target word it may have been added for and guess what happens? Your brain has context that your brain would seek out otherwise, but also by having that context, you will have an automatic memory trigger; you’ll even be able to recall where you got that piece of context (see the bigger picture). This lightens the load on your brain. Everything you deal with in Chinese will likely be in some form of context. Speaking, listening, and reading are almost always in context. By the time it’s necessary to deal with Chinese only on a single vocab basis (does it exist?) , it won’t matter, because by that time, you’ll be so solid in the language. Keep your decks personal. Whatever you put into your Anki, should be something only you didn’t know that you came across—your Anki will be your Chinese level. Of course, you can supplement your learning with listening or even use Anki for listening, but that’s another beast that has yet to be un-caged.

    1. Olle Linge says:

      I agree that what you present is a valid alternative that would work well for many learners and this is something I should either add or write about somewhere else. However, I don’t think this is a mistake. The reason is that it takes much, much more time to create the cards you’re talking about and it also takes much longer to review them. I spend an awful lot of time reading and listening to Chinese outside Anki and I don’t want to bring all my Chinese into the program. I want something I can spend five minutes with here and there while waiting for the bus and that’s what I have. I get the context from exposure in general. Still, I don’t use only one type of cards nowadays and do exactly what you suggest whenever the interesting thing I want to remember isn’t limited to a word. If I started learning another language all over, I might try what you suggest, but that doesn’t mean that what I’m doing now is a mistake.

    2. Sara K. says:

      I actually think it’s good to have cards, even high-level vocabulary, isolated from context (note: note all of my Anki cards are isolated vocabulary, and my decks are personalized – I do not import from strangers’ decks).

      If I just keep the vocab item only in context when I review, I find that I am able to recognize that vocabulary in similar contexts, but not in different contexts. If it’s a bit of vocabulary that’s only used in a single context, that isn’t a problem, but having cards without context helps me be able to recognize that bit of vocabulary in very different contexts.

  12. Ken Wong says:

    You have put a lot of thought into your well detailed report on SRS, well done. Overall, I think its a very useful and helpful comment you have made. Since the beginning of this post technology has certainly made some big advances, tablets and iPad etc. I imagine you have tested or use the free flashcard apps available, for example Flashcards+ that allows you to download vocabulary from a variety of sources, such as Quizlet. If users want to pay, they can pay a couple of dollars and get the voice function. I think for high school students, Anki would be an expensive option when there are similar, but perhaps not as many functions.

  13. I just wanted to point out that Hanping Chinese Dictionary Pro (and Hanping Cantonese Dictionary) for Android includes Anki support. When you star a word in Hanping, one or more flashcards are (optionally) auto-exported to AnkiDroid. Hanping also supports bulk-export of starred lists to Anki.

    Furthermore, in AnkiDroid the templates (generated by Hanping) allow the user to play audio, jump to various websites and click back into the Hanping app. Colored Hanzi, Pinyin/Zhuyin, Simp/Trad/both all supported (and configurable by modifying the CSS only).

    Here is a demo: https://www.youtube.com/watch?v=dvAlXIxVx5E

    I personally spent a long time earlier this year, working with the volunteers at AnkiDroid – writing lots of code for their app – to help make this possible.

    I also created a HSK1-6 deck using the same templates. Works best when used in AnkiDroid with one of the Hanping dictionary apps installed:



    Mark (Hanping developer)

  14. sarah says:

    I downloaded Anki after reading this article. I find that I could only review 20 cards everyday. Did you change the setting or something?

    1. Olle Linge says:

      You need to change the number of new cards shown per day. The default limit is 20. I think you do this in the study options, but it might vary between platforms and I don’t have Anki here. It’s a simple setting that you need to change, though, nothing wrong.

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