What is More Effective: Explicit or Implicit Grammar Instruction?

Grammar is a divisive word. If you admit you teach grammar, you could be shunned in certain ELT circles. And even for those circles that do accept grammar, the debate still rages about whether it should be taught directly (explicitly) – echoing “traditional” or “out-dated” methods – or indirectly (implicitly), more in line with more modern or “post-modern” methods. While the debate won’t easily be put to rest, a lot of evidence has come out against implicit grammar instruction as ineffective or less effective than explicit instruction. If you are still on the fence, this 2010 meta-analysis by Nina Spada and Yasuyo Tomita should help you make up your mind.

Introduction and Definitions

Spada and Tomita analyzed a total of 41 separate studies (in 30 publications) between 1990 and 2006. 63% of these studies were based on implicit grammar instruction. The authors calculated effect sizes for each study and compared each group’s average effect size to come to a conclusion about which type of instruction was more effective, on what type of linguistic features, and for how long. The authors categorized studied by instruction type, complexity, and type of knowledge based on the following definitions:

  • Instruction Type
    • Explicit instruction was defined as any instruction that involved rule explanation, language contrasting, and metalinguistic feedback.
    • Implicit instruction was defined as instruction that did not involve rules or attending to any form.
  • Complexity
    • There are numerous ways to measure complexity. The authors chose linguistic complexity based on the number of transformations a particular form had to go through.
    • Simple language features were those forms that included one transformation rule and one or two transformations.
      • An example would be article usage, tenses, plurals, etc.
    • Complex language features were those that involved multiple transformations.
      • Question formation, passive voice
  • Outcome Measures
    • Explicit knowledge1, i.e. knowledge of rules, is knowledge measured by controlled tasks such as metalinguistic judgments (judging whether a sentence is correct or not), multiple-choice tests, scrambled sentences, and “constrained constructed responses” that ask learners to produce an utterance.
    • Implicit knowledge, i.e. the spontaneous ability to use a grammatical form, was measured by free writing, oral picture descriptions, information gaps.


The results indicated that explicit instruction was more effective for both simple and complex language features. In addition, explicit instruction led to both greater explicit and implicit knowledge. Finally, explicit instruction was also more effective in the long-term (as measured by delayed post tests). One result that surprised the authors: the largest effect size in this study was of explicit instruction of complex language features on implicit knowledge (measured by “free constructed response” tasks). Implicit instruction only showed a medium effect size (some effectiveness) for simple language features on free tasks.


The authors point to a few caveats about their findings:

  • It is hard to tell if measures of implicit knowledge are really measuring spontaneous production or automatized declarative knowledge.
  • If they had looked at complexity in a different way (e.g. pedagogical complexity – how difficult it is to teach a feature), the results may have turned out differently
  • The number of studies they included that had delayed post tests were low. More research needs to use delayed post tests.

Other caveats or insights pointed out by previous commenters2:

  • The study does not state how much explicit instruction is necessary.
  • The study does not support teaching grammar in the sequential order in which most coursebooks present it.

Practical Implications

The main takeaway from this article is that in almost all cases, explicit instruction of grammar is superior to implicit instruction. This is supported by a previous Research Bites article that discussed how minimally-guided instruction may be detrimental to the learning process. Explicit instruction of grammar does not mean harking backing to the times of grammar translation, rote memorization of conjugations, or the focus on grammar McNuggets. Explicit instruction can come up quite organically in any class, from PPP, to TBLT, to Dogme. It can and should be embedded in meaningful communication. According to Dr. Spada in a personal email, “…explicit attention to language form does not exclude attention to meaning/communication/content other than language. Furthermore, most of the research investigating the effects of instruction on L2 learning indicates that a combination of language-based and meaning-based instructions works better than an exclusive focus on either one.”


Spada, N., & Tomita, Y. (2010). Interactions between type of instruction and type of language feature: A Meta‐Analysis. Language learning, 60(2), 263-308. Access online here.


  1. Originally, I used the term “declarative knowledge”. However, Dr. Spada pointed out in an email that “declarative” is often contrasted with “procedural”. In the article, they used the term “explicit”: “While declarative knowledge is considered to be the same as explicit knowledge this is not the case with procedural and implicit knowledge.   So while you are technically correct that we measured learners’ progress in terms of their declarative L2 knowledge and their implicit knowledge, we used explicit & implicit as the contrasting constructs for L2 knowledge when discussing the findings.”
  2. This article originally appeared here. Thanks to comments from Geoff Jordan forcing me to rethink how I presented the study, I was able to write a much clearer version here while including some of his concerns.


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Anthony Schmidt
English language Instructor at University of Tennessee, Knoxville
Anthony Schmidt is editor of ELT Research Bites. He also has his own blog at anthonyteacher.com. Offline, he is a full-time English language instructor in a university IEP program. He is interested in all aspects of applied linguistics, in particular English for Academic Purposes.

7 thoughts on “What is More Effective: Explicit or Implicit Grammar Instruction?”

  1. Hi Anthony,

    You’ve mentioned a few caveats; another is the (scant) attention paid to how the 41 studies measured immediate and delayed learning.

    There’s also the evidence from several reviews of the literature (e.g. Mackay (2012) and from 3 meta-analyses since 2006, (see Long, 20125, p.55-57) which found strong evidence for the efficacy of recasts.

    So the Spada & Tomita article must, as I’m sure you’ll agree, be considered as only part of the evidence, and I think we should conclude that the controversy about implicit and explicit grammar instruction continues.

    Long, M. (2015) “SLA and TBLT”. Wiley.

    Mackey,A. (2012) “Input, interaction, and corrective feedback in L2 learning”. OUP.

    1. Hi Geoff,

      Thanks for commenting!

      My summary did not include the information about how they measured immediate learning. However, that information is included in the article. It was measured based on the narrative of the articles included in the meta analysis. According to them, immediate learning was measured by post-tests occurring 4.89 days after treatment, on average. Specifically, “Our examination of the narrative
      descriptions in these sample studies led us to code “within one week after the treatment” as 3.5 days (n = 10) and “on the first day after the treatment” as 2 days (n = 2)”. For delayed feedback, 17 studies were included and these delayed post-tests occurred 4 weeks, on average, after treatment. The post- and delayed-post test types are briefly described in the outcome measures part above. More detailed examples are in the study.

      I’m not sure of the relevance of corrective feedback in terms of this article as it was looking at instruction type and not measuring CF. I have read articles that support both explicit feedback and recasts. My favorite article on the subject, really points to the effectiveness of such feedback as context-dependent: “The most effective teachers are likely to be those who are willing and able to orchestrate, in accordance with their students’ language abilities and content familiarity, a wide range of CF types that fit the instructional context (Lyster, Saito, & Sato, 2013).

      To your final point, of course I agree that this “controversy” is not an open and cut case based on this 2010 study. There are so many variables in play that having an end to the controversy is not possible. What I am suggesting research points to is the effectiveness of explicit grammar instruction in certain cases (e.g. complex linguistic features) for certain effects. Likewise, as I suggested in my previous Bite, explicit instruction in general is likely more effective in specific situations (low-proficiency). Related to that, level of proficiency is likely a large mediating factor in corrective feedback, possibly making what looks on the surface to be a recast to actually be explicit correction (http://www.anthonyteacher.com/blog/researchbites/research-bites-rethinking-implicit-explicit-feedback).

      What I think this research gives us is not a final opinion on the matter so much as confidence in applying certain pedagogical techniques in certain situations, and only to a certain extent.

      Lyster, R., Saito, K., & Sato, M. (2013). Oral corrective feedback in second language classrooms. Language Teaching, 46(1), 1.

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