...per Chinese teacher Terry Waltz, it takes about 50 exposures for most words to be retained in long term memory...
The kind of beginner content I'd like to see, u/Elevenxiansheng, Reddit r/ChineseLanguage

I gather that Terry Waltz is the author of this blog and a comprehensible input blog (which seem to overlap). However, I didn't immediately find a source for the above claim, neither by using the site's search features nor by Googling Terry Waltz 50 exposures.

Question: Does it take "about 50 exposures for most words to be retained in long term memory"?

Basically, I'm wondering if this is well-known in the language learning community, and perhaps there is evidence (or even research papers) to support the claim. Another redditor seemed to act like it was common knowledge. Or perhaps the redditor is mistaken.

  • I know Terry. She is a great person. She learned Chinese from scratch so I would believe anything she says and not take it with any grains of salt. Also, it depends on the language and how close or far away it is to one's own.
    – Lambie
    Commented Feb 22, 2023 at 19:17

2 Answers 2


There are two important things about Terry Waltz that you need to know:

  • she teaches Chinese to native speakers of English, so not everything she says about learning Chinese automatically applies to languages closer to English (or closer the native language of pupils or students), and
  • she uses TPRS / Teaching Proficiency through Reading and Storytelling, which focuses much more heavily on comprehensible input than many other teaching methods.

I could not find a statement by Terry Waltz mentioning 50 exposures, but I found the following comment by her on a blog post (14.05.2010):

In classroom teaching using comprehensible input, we usually aim for 70-80 exposures in novel contexts during the first day of presentation, then regular "refreshers" when the item is presented in the course of input over future lessons. 10-20 isn't nearly enough, especially if the language is not highly similar to English. For a cognate, maybe. For anything else, not really.

So she admits that the linguistic distance between the native language and the target language impacts the number of required exposures, though it is not clear how much. The influence of the teaching method is not mentioned at all.

For a demonstration of teaching Chinese using TPRS, see the YouTube video TPRS DEMO: Day 1 Mandarin, Terry Waltz (18 minutes, 04.03.2015; notes that appear on the video explain what she is currently doing and why).

In an earlier response to a somewhat related question, I had found that 8 to 10 revisions were required. Fooziyeh Rasouli and Khadijeh Jafari wrote in their paper A Deeper Understanding of L2 Vocabulary Learning and Teaching: A Review Study (International Journal of Language and Linguistics, January 2016),

Webb (2007) explains that for each repetition of a word, at least one piece of word knowledge is acquired; therefore, a typical learner should meet a word about 8 to 10 times to obtain full word knowledge. What is worth mentioning here is the intervals between the repetitions. Nation (2001) refers to the conducted studies on memory and reports that "most forgetting takes place immediately after first encounter with new information. That is, the older the piece of knowledge, the more slowly it will be forgotten. This suggests that the first several encounters should be close together, with later encounters spaced farther apart" (p.24).

"8 to 10 times" is a number of exposures that, according to Terry Waltz, "isn't nearly enough", but I think the teaching method and, consequently, what exactly constitutes "exposure" make a crucial difference here.

  • Oh! I found a similar claim in a book linked in the TPRS Wikipedia page: Experienced TPRS teachers can provide 50 to 100 repetitions of key words during the teaching of a 30- to 40-minute [personalized mini-situation]. Commented Mar 12, 2020 at 11:41
  • @RebeccaJ.Stones Thanks for the link. Blaine Ray is a name I've come across before in this context. I'm beginning to suspect that the number of required exposures is strongly related to the teaching method, but this requires more research.
    – Tsundoku
    Commented Mar 12, 2020 at 11:59

I know a little bit about what Waltz is talking about.

The amount of "distance" from the native language to the learning language is important, as is the amount of cognates present. Other factors include word length (very long or very short words require more repetition since they are harder to fix in auditory memory / harder to distinguish in speech) and to some degree emotional involvement (drop the "f--" word accidentally in a classroom and see how many reps THAT one takes -- it's far below 50.)

8 to 10 revisions is nowhere near enough for a student to acquire a word (which means to have it firmly in the subconscious so it can be accurately output without effort or thought). I would really like to see Webb or anyone else teach new words to unconscious correct comprehension and production in only seven repetitions with beginners or intermediates. Most people are only figuring out which word is which at that point.

When we teach Chinese reading (which we do without pre-memorization of characters) we need a strong Chinese voice in the head to "push" reading comprehension since there is zero phonetic information available to novice readers of Chinese. You have to be able to "hear" the language in your head to read. That requires a lot of repetition. If you teach French, you need some voice because of spelling challenges, but the text will support you. If you teach Indonesian to English speakers, you need less voice still because the phonetics are very straightforward. If you teach Spanish, less still because in addition to very reliable phonetics, you have lots of cognates to fall back on.

So while it's true that in my experience teaching multiple languages, Chinese to English speakers requires more reps than Spanish to English speakers, the biggest divide in practice (and results) that I have observed in the past 30 years lies in whether the teacher stresses repetition -- which needs to be unpredictable repetition. Not "I can look ahead in the book" repetition, not "I know what the next question is going to be" repetition. And to generate that level of unpredictable meaningful language, usually you're talking about a CI (Comprehensible Input) based teacher. (I am NOT a TPRS teacher, though TPRS is one of the things I use. I teach using Comprehensible Input, or more correctly in my opinion, "Comprehended" Input, since anything that's not understood is noise to students.)

The more years I teach language, the LESS vocabulary I include, and -- counterintuitively -- the more proficient students become in the same amount of time. The reason is that they are getting more repetition of the same language elements, combined in unpredictable ways, over the same amount of time. Narrow and deep. But like Cold Character Reading (direct-to-text Chinese reading), which no one believes until they see it happen for themselves, Comprehensible Input is another one of those things that teachers dismiss until they experience it themselves.

I'm very surprised and a little weirded out to see people discussing me on StackExchange, though. lol

  • I just don't get how anyone around here knows more about this than you do.. I take everything you say with no grain of salt whatsoever. :)
    – Lambie
    Commented Feb 22, 2023 at 19:20

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