Setting :

Suppose a magic potion could make the person drinking it able to understand, memorize and re-use any word, idiom, sentence structure or grammatical rule they hear.

(EDIT : It's not memorizing and repeating stuff like a parrot but trully being able to use a new word/rule/idiom with the same ease as the person they heard it from, as if they've already been using it for years.)

The potion's learning-boost lasts 10 to 30 minutes, depending on how many new things the person hears. After that the drinker needs a solid nap and wakes up with a painful headache.

A group of people decided to teach their language to someone whose first language is completely alien to them.

Each session begins like a relatively well-thought lesson, with two or three of them reading to the student texts and words lists they prepared (Not sure I'll keep it this way, being able to learn from several people at the same time sounds like a loophole).

After a few minutes, they are generally interrupted by the student, who was kinda kidnapped and always tries to ask lots of questions, or by one of the teacher who starts criticizing the words choices of another. It then quickly degenerates in family squabbles, general discussions on linguistics and teaching methods, gossips about the neighbours, more family squabbles or, more rarely, some useful explanation on who they are and what their plans for their student's future actually are (they often disagree on the last point).

The lesson ends when the student falls asleep on his chair. His teachers then untie him, put him in bed, and go back to either more squabbling or preparations for the next lesson. The student is left alone in his cell for the rest of the day.

My thinking :

Apparently, knowing the top 3000 most used words of a language is enough to understand 94% of oral speech.

An average speaker talk at rate of between 100 and 125 words by minute (source : Wikipedia). 5 minutes of actual lessons, given by 2 people at the same time, would teach the student at least 1000 new words by lesson (assuming they don't repeat themselves).
These words won't always be the most commonly used ones, as one teacher delights himself in listing obscure or technical vocabulary. After 5 days, the student would know at least 5000 words, ranging from common to archaic.

Note that this calculation doesn't take into account grammar, idioms or figures of speech.

People arguing tend to speak fast, sometimes at the same time, and maybe use some useful expressions, so I guess it could count as actual lessons.

What I'd like to check :

With a regimen of one lesson every day, would it be realistic for the student to be able to speak fluently his new language in less than a week ?

If not, what would be the minimum number of lessons needed ? Is there something crucial these lessons lack ?

Note : I do know the way this potion works is basically impossible and requires a fudge load of handwaving. But given these premises, how many lessons would it take and what important parts of the spoken language is missing from them ?

Note 2 : I made the lessons part words lists (written for the lessons so that they mostly contain unique words), part texts read aloud (complete sentences with correct structure and grammar), part heated discussions so that they include vocabulary, grammar and interjections.

Note 3 ( based on answers) : The student drinks the potion, not the teachers.

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    $\begingroup$ This is probably a good time to point out most children pick out grammar concepts and actively use them without any knowledge or understanding of the grammatical concept they are using. Good chance I've just used grammar concepts in this statement that I don't fully understand as well. $\endgroup$
    – Twelfth
    Aug 23, 2016 at 21:48
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    $\begingroup$ @Twelfth The subject "understand" them the same way anyone understands the grammar concepts they use in everyday life. Basically the student will end up understanding and using words the same way his teachers do. Since in my story the teachers are well-learned, though unorganized and quarrelling a lot, the student should not end up with half-understood words or poor grammar. It's more knowledge transfer than perfect memory. $\endgroup$ Aug 23, 2016 at 22:13
  • $\begingroup$ I'll stick to my answer...after a week with some magic memorization, you'll have a person at this point en.wikipedia.org/wiki/Pidgin $\endgroup$
    – Twelfth
    Aug 23, 2016 at 22:51
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    $\begingroup$ @Twelfth Okay, don't worry it's perfectly ok to answer "No." with an explaination consistent with the settings of the question. I know what pidgin means, long years me using it often. That's why I included texts and actual conversation in the lessons. So the drinker would also "absorb" the correct way to form sentences and conjugate verbs. $\endgroup$ Aug 23, 2016 at 23:34

5 Answers 5


I'll set aside the issue with a speaker hitting that many unique words a minute for this answer.

There is much more to a language than simply understanding what a word means...little subtleties that you probably frequently use in your native tongue that are a complete pain to someone learning to speak. English is actually straight forward in a lot of it's grammar...no noun gender or lacking complex conjugation for example (I run, you run, we run, etc is straight forward in english...in French you better be ready to alter the words ending according to its regular conjugation based on it's grouping/gender and recognize when it's an irregular...or you'll be saying the wrong one). But English has stupidly complex parts, especially in regards to tenses (having been had, or will be having had?). Are small, smaller, smallest 3 separate words, or one word with -er-est endings applied? Would you recognize when a suffix was added to make a noun diminutive?

There's also issues in pronunciation...if your mother tongue lacks tonals, odds are you aren't going to be able to understand whether a Mandarin person is talking about their mother, horse, hemp, or bother (google that one if you don't get it). An English person won't pick out the nasal oe eo in french, and a non Germanic language speaker is going to horribly stumble on consonant clusters...if your tongue isn't trained to touch your teeth, are you ever going to get a th sound out, or just a d? I guess your potion also teaches one how to move their mouth properly?

And this is only a few of the issues...grammar is a beast and there is a good reason English grammar is taught from grade 1 to university.

That being said, there is no way this person is fluent. Can they converse with another person in this language? Quite likely. However they will be communicating in a pidgin form of the language...pidgin simply meaning language devoid of grammar. lake fish want me. You'll likely get what I meant with those 4 words...pole string boat now fish get! You get the idea...surely not fluent, but can definitely communicate.

  • $\begingroup$ Thanks for your answer. They do use a lot of unique words per minute because they prepare their lessons. They write both texts (containing correctly formed sentences) and vocabulary lists, knowing how the potion works. Take a dictionary and read the words aloud, you can hit the 100 distinct words per minute with very little training. Yes, the potion makes the drinker able to use words as well as the people they hear them from (including pronunciation). I do know it doesn't work like that in the real world. It's a fantasy setting that uses magical brain-to-brain knowledge transfer. $\endgroup$ Aug 23, 2016 at 22:58
  • $\begingroup$ Don't worry, I realise how hard it is to learn a foreign language IRL :) . I wasn't a very good student in school and basically had to start re-learning English at 20 years old. It was difficult and took me a lot of efforts and time to be able to hold even basic conversations. $\endgroup$ Aug 23, 2016 at 23:03
  • $\begingroup$ @SpaceLizard - I guess this is the nature of a magic potion question with a 'reality-check' tag on it while working with something as loosely defined as 'fluent'. In any case, you will go from no understanding to a few words to kinda pidgin to childlike to fluent...your timelines can easily be defined by magic after all. Is it realistic? Of course not, hence why it's called 'magic'...if we came up with a realistic way for this to work, it wouldn't be magic anymore would it? ;) $\endgroup$
    – Twelfth
    Aug 23, 2016 at 23:06
  • $\begingroup$ Yeah -_- I tried to make it clear that I wanted to check my lesson plan, not if the potion could work that way IRL. Is there a tag for "Checking magic rules coherence and effects but not if said magic can exist in the real world"? $\endgroup$ Aug 23, 2016 at 23:40
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    $\begingroup$ @SpaceLizard lol no, but I suspect there needs to be. Honestly from a complete story standpoint, do what you want...how many people are going to nitpick your book because they disagree with the effects of a magical potion? You could have some fun with a character...his teacher decided to pig latin every 20th word. $\endgroup$
    – Twelfth
    Aug 23, 2016 at 23:46

The concept of "fluency" in a language is avoided in linguistics, because it's not possible to divide people into "fluent" and "not fluent." If fluency is used, it is used on a continuous scale. Thus, we have to use a little creative license.

Fortunately, there's prior art. Daniel Tammet famously learned conversational Icelandic (considered to be a particularly hard language to learn) in one week. He learned it sufficiently well to then go on the air on a radio station in Iceland and accept calls from radio listeners.

Obviously he put a bit more into it than merely a 5 minute lesson every day. I don't think you could realistically fit 1000 new words into a lesson. The whole reason why the top 3000 words is enough for most conversation is that we reuse most of the common words very frequently, and a single usage is not always sufficient to understand all nuances of the meaning. However, you are talking about magic, so you may have some room to play with.

  • $\begingroup$ Thanks for the answer. I tried reading pre-made lists of 100 words aloud, it's feasible. The teacher don't need to explain definitions, their own understanding/usage of the words (including the nuances and pronunciations) is transfered to the student as soon as they say it out loud within earshot. $\endgroup$ Aug 23, 2016 at 23:14
  • $\begingroup$ Should I change "Speaks fluently" to "Pass for a native speaker" ? Which one is clearer ? I may have to rewrite entirely the question. I left out the potions adverse side-effects (forgetting your own native language, losing memories, and having to re-learn how to control a few bodily functions) from the setting to make it shorter ; and now it looks like most of the answers focus on the whole thing sounding too easy compared to how long it takes to learn a foreign language in the real world. $\endgroup$ Aug 23, 2016 at 23:26

I don't think your person will be fluent (that is, pass for a native speaker) in less than a week of lessons. I also don't think that what you need to make it happen is more lessons - that isn't the problem.

So, after a week, he will be speaking pidgin. Even if he has all the vocabulary in his head, even if he has all the grammar lessons hand-waved in - he will be speaking pidgin. Because the inside of his head is still his. Unless the potion destroys his native language, and overwrites his linguistic memories - he is going to think in English, compose his thoughts in English, remember in English, transpose English grammar and the rules of the new language, muddle up English phrases and ways of saying things with the new language's conversational patterns and vocabulary. Even perfectly recorded in his head, it still is, ah, competing with his original language - and he has had a lot of practice with that language and its rules and he knows he knows them, so he will reach for that one, first.

You can hand-wave the magic-lesson-learning, yes, but it is much less feasible to hand-wave the inside of a person's mind, at least if you don't mean to destroy their minds. So what does he actually need? Not more lessons, I agree that your 20-30 minute lessons will cover most of the vocab and even a fair chunk of casual grammar, but some real practice.

He will have to slow down and think about it. He will have to deliberately separate this new language from his native one - and it will have to be a deliberate choice, lest he choose to keep mangling it as a form of defiance if he was kidnapped and not actually persuaded to learn, or try to "pass" for his captor's plan. And he will need to speak in this new language, with others, to improve his fluency, to become familiar and comfortable with it.

Once he has decided to try, and is slowing down and thinking ahead so as to speak the language - he will be speaking like a competent speaker for which this is a second language. The magic lets you jump over the intermediate steps, he knows the words, and he knows the rules. But he will be hesitant and speak slowly, since he has to dig each word up out of his memory (even the memory of vocab of our native language can take a bit to sift through) - magically added or not, it is a word he hasn't used much, so takes a second to think of. And part of that hesitancy is simply being unsure of the words or phrases, even if has a good guess, even if he is right. He needs to build up confidence in the magic potion's work.

Even so, he may not grasp certain unusual or exotic usages - especially if he only heard them once, or not under the potion, or was also told a rule which contradicts them. He will likely have a certain formality of speech, especially with those grammar rules they managed to teach him, he will probably favor those over those he picked up from hearing them speak. Native speakers are not only much less concerned with grammar, having gained it (and when to break it) more organically, they also can posses a certain deliberate disregard for the rules - like, "An it is my language and I'll oosh with it if I wanna!"

So for fluency, he needs practice again - if the potion is very good, perhaps a week of conversational immersion. I would equate this to someone fairly fluent (...ish), who has not spoken the language in a while and needs to re-acclimate themselves before becoming comfortable with them again. The magic placed it in his head, sure, but he needs to get comfortable with it, and practice reaching for this language, and its rules, and conversational patterns, instead of his native language. He needs, almost, well, needs to start thinking in this new language. And he needs to learn how he should react when someone says a phrase or word he still doesn't know, or makes cultural or historical references - what excuses will work (and for what kinds of words), and how to gloss over his ignorance until he can find someone safe to ask.

If your captors plan ahead, they might include some kinda cultural immersion in their week-of-lessons, or even overlapping that week (starting once a couple lessons are in) - but even if not, even one more week will do wonders, having papers to read, listening to conversations happening "next door" (they know he will eavesdrop, but "overhearing" his captors is a good incentive for him to learn), plenty of people talking to and about him, to exercise the knowledge dumped in his head and start using it. Learning history and customs and culture. Learning how to pass, which is rather more than learning just how to speak understandably, as all the spy stories should tell you.

By the end of that, he might be able to pass as a native speaker - kinda. Maybe one who was isolated, isn't up on current lingo or slang much, who seems to have learned more from strict teachers and books than a lot of casual conversation... but still a native speaker, just one from a strict home or something. He still may mess up a bit if startled or rushed (and probably will always swear in English, for example) - but he can get much closer to passing this way.

(Random side note - my instincts say that after he speaks the new language for a while, going back to English might hurt, especially if the magic, er, magically de-prioritized that language for optimizing the learning of this one. Messing with the mind has a price, and usually more than one. But that's just my thought.)

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    $\begingroup$ Thanks for the answer. I left the negative side-effects of the potion (and a lot of other stuff) out to keep the question shorter, but it basically erases most of the native language, a bunch of memories and in some rare cases the drinker even have to re-learn things like walking or controlling their bladder. Indeed, lak of practise seems to be the biggest flaw of these lessons. I'll put a couple other captives (native speakers of the new language) in the same cell, to make him practise during rest of the day. $\endgroup$ Aug 24, 2016 at 7:28
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    $\begingroup$ @SpaceLizard - Erasing his language is going to have really big repercussions on his mind and memory, ouch. It will have to rewrite so very much of who he is and how he thinks himself to be - but it does avoid the problem of competing languages, so now you just have to get him to practice. And other captives will give him a reason to speak to them his captors might not manage, to try to escape. $\endgroup$
    – Megha
    Aug 24, 2016 at 7:56

No way

An average speaker talk at rate of between 100 and 125 words by minute

But these words repeat. A lot.There will be much less new words. The latter, the worse.

able to understand, memorize and re-use any word, idiom, sentence structure or grammatical rule

Sentence structures and grammatical rules are problematic. Think about your own language. Do you even know what grammatical rules you are using?

with two or three of them reading to the student texts and words lists they prepared

OK, this teaches him to understand. Still, having theory behind sentences, and some words, does not make you fluent speaker. For that you need practice. A lot of it. Enough to never consciously think about rules or word choice. And your victim is not getting any.

  • $\begingroup$ Thanks, I'll clarify the question. I meant to say that the drinker assimilates the word. As in they would have no problem to use it in a sentence after hearing it once. Yep it's nothing like reality, I know. It took me a really long time to learn enough English to hold a converstion. $\endgroup$ Aug 23, 2016 at 21:48

Why don’t you try it yourself? You can even record the sessions and edit the scenareo for posting on YouTube. Put yourself in the place of the learner; pretend to be tied up. Have people who are native speakers of some other language coached to improvise the behqvior of the teachers.

Follow each session with a video where you express what you managed to get out of it.

My guess is that it will be useless and you’ll pick up a few words only, those words not being part of the intended lesson but what the teachers say when arguing.

  • $\begingroup$ Yes, I know it's completely impossible IRL. This setting uses a lot of magic/unobtainium/brain-to-brain knowledge transfer stuff. I know the way this "magic potion" (not an actual potion, but saying it like that makes the question shorter) works is very weird. I'm worried about the time it would take to learn a language using it as it is and parts of the language that aren't present in these lessons as they are for now. I made them part words lists, part written texts (read aloud), part heated discussions so that they include vocabulary, grammar and interjections. $\endgroup$ Aug 23, 2016 at 22:32
  • $\begingroup$ I don’t see what the potion had to do with the captive learning the language “for real”. Were the teachers using the potion to talk to the captive? $\endgroup$
    – JDługosz
    Aug 23, 2016 at 22:42
  • $\begingroup$ The captive drinks the potion. The potion affect the captive, giving him the ability to use any word/grammar rule/idiom with the same ease as the person they heard it from, as if the knowledge was transfered from the speaker's mind to the hearer's. $\endgroup$ Aug 23, 2016 at 22:46
  • $\begingroup$ That's not clear from the narrative. What’s the point of lists/lessons if he understands everything magically while under the spell? $\endgroup$
    – JDługosz
    Aug 23, 2016 at 22:49
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    $\begingroup$ Or write your own answer based on what you learned from the different posts. That’s more common on other SE’s but allowed here on WB just the same. $\endgroup$
    – JDługosz
    Aug 24, 2016 at 8:06

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