How to Master a Language for Life
This age-old question, debated by educators and learners alike, hinges on the idea that someone who knows a language inside-out may or may not be the best person to teach it to others. Let’s take a nuanced look at this complex debate and try to answer the question once and for all.
As a foreign language learner and educator, you always prefer and recommend native speakers as teachers, all other factors being equal. Why?
I previously explained how communicating with native speakers tends to feel like a more authentic social interaction, which is an essential element of successful language acquisition. Native speakers often have had a rich cultural experience growing up with the language you want to learn, which can help to motivate and guide your own studies, in addition to providing insights into the culture that is closely linked to your target language.
But there is an even more fundamental advantage to native speakers as teachers: the implicit knowledge that, by definition, they possess of the language.
Of course, beyond subject matter knowledge, foreign language teachers (like any other type of educator) should ideally possess a series of characteristics to be highly effective: they should be patient, empathetic, engaging, demanding, attentive, and skilled at providing clear explanations and regular feedback.
It is therefore unquestionable that some nonnative speakers, possessing many of these qualities to a high degree, can be excellent foreign language teachers, and that, conversely, some native speakers, lacking them, may not be effective language instructors at all.
Evidently, however, the above traits can be equally possessed by natives and nonnatives and therefore are not necessarily relevant to the choice between these two categories of foreign language teachers.
Now, if we were to erroneously define a native speaker as one that was born in a specific country or possessed a given nationality, then it would be an unimportant qualification for a language instructor. Native speakers rather should be defined precisely by their communicative mastery in a language, almost always obtained by having interacted primarily in that language, with other native speakers, for a decade or more—most often during their formative education as pre-teens and teenagers. In this regard, being a native speaker of a language is usually, but not always, the same as that having that language be your first or “mother” tongue.
When the concept of a native speaker—one who communicates with spontaneous and intrinsic lexical, grammatical, and phonological mastery—is thus properly understood, it becomes clear that being a native speaker is synonymous with communicative knowledge or proficiency in a language.
Some people point out that nonnative teachers often have greater knowledge of explicit grammar than native speakers and consider this to be a significant advantage. I will readily concede that nonnative speakers who have learned a language through a grammar-intensive approach tend to have greater explicit knowledge of abstract grammatical rules and terminology than native speakers who have not received the same training. Therefore, if your goal were to learn grammar rules and terminology in a language, you would rightly seek out a teacher that had that knowledge, and that might often be a nonnative speaker.
However, since your goal is to communicate well in your target language, in speech and in writing, then abstract grammatical knowledge is of little relevance, and instead you should seek out teachers that have the greatest communicative mastery, both oral and written (in addition to the other traits that make for an effective teacher). As I have pointed out, when properly understood, native mastery of a language is synonymous with that communicative proficiency.
It is important to note that, when it comes to language mastery, being a native speaker is not sufficient for most purposes. Teachers should also be highly literate—well-read and good writers and thus capable of properly guiding students in developing their own reading and writing skills, including through skilled essay correction.
Native speakers may be competent in dialects and language registers that are not standard or sufficiently formal. For example, here in Brazil I have met uneducated country folk who are impressively eloquent and have a vast vocabulary. Yet I would not recommend them as teachers of Portuguese as a foreign language because, while their language skills may be just as admirable and correct from a linguistic point of view as that of a cosmopolitan, highly educated urbanite, their language register is not compatible with foreign students’ goals. Almost all students want to learn a universally applicable, standard language register. For that reason, in addition to the abovementioned importance of literacy, teachers should generally be university-educated native speakers.
Okay, native speakers, by definition, have superior communicative mastery in my target language. But is that relevant to their ability to effectively teach me?
Let us first consider research in education more broadly. It may seem obvious that teacher subject matter knowledge is one out of several important characteristics that contribute to teaching quality and student outcomes. Like most people, I prefer to be taught by someone with deep, intimate knowledge of a subject. However, this correlation has been the subject of a great deal of debate in educational literature. Unfortunately, few rigorous empirical studies exist.
One of the few studies with a large enough sample size (9,556 middle-school students and 181 physical science teachers) and a rigorous, well-designed methodology to address this subject was conducted by researchers at the Harvard-Smithsonian Center for Astrophysics and published in the American Educational Research Journal in November 2013.
Most researchers and school administrators use proxies for subject matter knowledge such as university degrees or certifications instead of assessing the knowledge directly. However, these proxies may not accurately reflect actual knowledge, so that what is being measured is not the correlation between subject matter knowledge and student outcomes, but rather the correlation between the latter and degrees and certificates.
The Harvard-Smithsonian study instead applied subject matter knowledge tests; interestingly, they used the exact the same test for teachers that was also applied to students. In other words, the researchers tested teacher mastery of precisely the content that they intended to help the students master.
The results clearly show that “student learning is related to teacher knowledge”; those studying with a more knowledgeable teacher showed significantly greater improvement than their peers, especially when scores on specific topics correlated with teacher mastery of those exact topics. In addition, teacher subject matter knowledge was a much stronger predictor of student outcomes than potentially confounding metrics such as years of teaching experience or university degrees. These findings are consistent with previous international studies, including ones in Belize (Mullens et al., 1996) and Brazil (Harbison and Hanushek, 1992) that showed strong correlations between teachers’ proficiency in mathematics and their respective students’ gains in the subject as measured by similar tests.
So subject matter knowledge is relevant to student outcomes, generally speaking. But what about language instruction in particular?
While the above study occurred in a middle-school environment, its unsurprising conclusion that teacher subject matter knowledge significantly impacts student outcomes is likely to be even stronger in language learning, for two reasons.
First, in the modern communicative approach to language learning, the teacher’s implicit language knowledge or proficiency exactly matches what students want to obtain. In other words, what the teacher is particularly specialized in—communicative use of the language, as opposed to academic knowledge about the language—is precisely what the student needs to acquire.
Second, teacher-student interaction is not only the vehicle for content to be transmitted, but it is the content itself. With respect to the speaking component of language mastery—the main reason for having language classes at all—conversation between teacher and student provides the substrate for student learning. Therefore, the teacher’s ability to manipulate language naturally and skillfully—i.e., generate the proper substrate—is probably more important to student outcomes than in almost any other area of knowledge.
So, you’re saying native speakers are better language teachers?
Not necessarily: nonnative teachers can be excellent and there can be valid reasons for preferring them in some cases. Nonetheless, all other things being equal, yes, I would always prefer and recommend skilled native teachers because of the communicative mastery they possess, which is highly relevant to student outcomes.
Can I try out a class with a native speaker today?
 It’s worth noting that the classification of a speaker as “native” is not always written in stone. Teachers, like speakers of a language in general, have varying levels of mastery. It is possible (though quite rare) for someone to become a native speaker of a second language, and it is also possible for a person to lose fluency and suffer from significant linguistic interference in their mother tongue. In subsequent paragraphs, I try to give a useful definition of what it means to be a native speaker, and why that is important.
 There may be other legitimate reasons for choosing a nonnative teacher, even when one has access to skilled native teachers. These revolve around the fact that the nonnative teacher has gone through the process of consciously learning your target language themselves, often as an adult: therefore, they may be especially empathetic to your challenges and be great guides through your learning process. So, the choice partly has to do with personal preference. On balance, I find that learning from someone with deeper mastery and full cultural and linguistic authenticity in the language far outweighs any advantage of a nonnative teacher. Ultimately, the key is having a teacher with communicative mastery of the language (even if not full native) in addition to the other qualities that constitute a great teacher.
 Sadler, Philip M., et al. “The Influence of Teachers' Knowledge on Student Learning in Middle School Physical Science Classrooms.” American Educational Research Journal, vol. 50, no. 5, 2013, pp. 1020–1049. JSTOR, www.jstor.org/stable/23526122. Accessed 7 Aug. 2021.
 The study also looked closely at teacher knowledge of student misconceptions, which also correlated positively with student outcomes. Though beyond the scope of this post, this finding suggests, analogously, that foreign language teachers becoming aware of common student mistakes, through experience and training, can better equip them to help students efficiently acquire a target language.
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