Introduction to Teaching with Comprehensible Input

Updated December 27, 2017

Teaching with Comprehensible Input (TCI) is a collection of approaches, techniques, and strategies for teaching language that prioritize the delivery of understandable and compelling messages in the target language 1. It is based heavily on the Comprehension Hypothesis of Stephen Krashen, which says that we acquire language when we understand what people tell us and what we read. In other words, there is no need for deliberate memorization of vocabulary or grammar rules. Instead, a firm knowledge of grammatical rules (a feel for correctness) and a large vocabulary gradually emerge as language acquirers get more comprehensible input (aural or written language that is understood) 2It takes many repetitions for the brain to acquire new words, and many more repetitions for it to master and internalize a new structure (“grammar pattern”). Acquisition takes time, and everyone’s acquisition goes at a slightly different pace. Krashen’s description of “i+1” means that we should be providing input just slightly above the student’s current level of acquisition.

In order to provide this massive amount of comprehensible input, comprehensible input-based teachers strive to teach at least 90% of the time in the target language in accordance with the ACTFL 2011 position statement. Several popular comprehensible input-based activities are TPRS, MovieTalk, Special Person Interviews, One Word Images, and Embedded Readings. Unlike TPRS, AIM, or OWL, teaching with comprehensible input (TCI) is not a method because it does not have a prescribed series of steps. Rather, it is a collection of research-based principles that informs what we do in our classrooms. For a brief introduction to comprehensible input, watch the short video of Stephen Krashen below:

TCI teachers believe that input must compelling, not just comprehensible. By talking about interesting things such as cultural topics and our students’ experiences and ideas, students want to understand what’s happening in their language class. If they understand, then they are acquiring! It’s so simple in fact that anyone can experience success in acquiring a language if they are taught with comprehensible input (even students with learning disabilities or students from other populations that are traditionally underrepresented in language programs). After all, virtually everyone is the world is successfully able to acquire their native language.

One thing that differentiates comprehensible-input based instruction from other foreign language teaching methodologies is our use of English. English is used to establish meaning. In other words, we quickly tell students the meaning of unknown words in their native language so that no one is left guessing. This is very different from an immersion or like-immersion setting in which students are forced to guess the meaning of words based on context clues, pictures, or gestures. We take advantage of the fact that the teacher and the students can already communicate in one language as they learn their second language.

Another differentiating feature of comprehensible input-based instruction is our view of output (speaking and writing). While all language teachers want students to confidently and spontaneously produce the language, we do not believe that speaking or writing exercises will improve the quality of students’ output. As Wynne Wong said, “A flood of input must precede a trickle of output.” Furthermore, in keeping with Krashen’s Affective Filter Hypothesis, we do not push for output. We don’t make students speak until they are ready to do so because if students are forced to produce too soon, the output will most often be incorrect as the brain attempts to use rules and logic to consciously construct language based on its knowledge of the native and any other languages it knows well or in part 3.

“What teachers see as ‘advanced’ (e.g. the subjunctive) is actually used quite early on by native speakers; other supposedly ‘important’ vocab (e.g. clothing) is not very frequently used” 4.

The final important principle of teaching with comprehensible input is that we shelter vocabulary, not grammar. In a traditional language class, students might be expected to memorize 30+ vocabulary words per unit. This is excessive due to the fact that for Spanish for example, learning the first 1000 most frequently used words in the entire language will allow you to understand 76.0% of all non-fiction writing, 79.6% of all fiction writing, and an astounding 87.8% of all oral speech 5. Given these numbers, it seems questionable that so many teachers would make students memorize large quantities of thematic words that seem important but that turn out to be surprising low-frequency. You can access free frequency lists for every language on Wiktionary. Essentially, comprehensible input-based teachers do things the opposite of other teachers. While traditional teachers teach a lot vocabulary but wait four years to teach “hard grammar” like the subjunctive, comprehensible input-based teachers use a limited vocabulary with all grammatical forms. So, teachers frequently use the subjunctive, the past tenses, irregular verbs, and the conditional with Level 1 classes. The students don’t know the names for grammar, but it doesn’t matter because grammar is taught through meaning (i.e., giving a translation).

Further Reading

This article was a mere introduction to teaching with comprehensible input (TCI). If you want to learn more about the research and beliefs that inform our practice, please read the philosophical articles below. If you are ready to learn more about how all of this works in the classroom, then read the practical articles.

Philosophical Articles

  • Why Switch to TPRS / CI: This post will discuss the benefits of switching to comprehensible input-based instruction, if you’re not already convinced. Also be sure to view the achievement results that teachers are getting with these methods.

Practical Articles

  • Introduction to TPRS: TPRS stands for Teaching Proficiency through Reading & Storytelling. It is a method for teaching with comprehensible input. The techniques of TPRS have spawned other methods such as MovieTalks, One Word Images, and PQA, which may be simpler activities to try immediately.
  • Pop-Up Grammar, Comprehension Checks and Circling are three of the basic techniques that are used in comprehensible-input based teaching.
  • Professional Learning Communities: Join some listservs, Facebook groups, and Twitter chats to learn and ask your questions to experienced teachers. They are truly indispensable.

Now Ask Questions

If you have questions of any kind, I encourage you to leave a comment below, and I promise to respond promptly. Also, if you have any feedback about this article (parts that were unclear, overwhelming, inaccurate, etc.) please let me know in the comments as well. I wanted to provide a thorough introduction to this style of teaching without being overwhelming, and I’m not sure if I was successful or not. I look forward to our discussions, and I wish you the best of luck on the next steps of your TCI journey.


Want to become a better language teacher? Try teaching with comprehensible input (TCI).

  1. Grant Boulanger, Teaching with CI.
  2. Stephen Krashen, Second Language “Standards For Success”: Out Of Touch With Language Acquisition Research.
  3. Terry Waltz, CI in Short (2012).
  4. Chris Stolz, Evaluation Is Overrated (2014).
  5. Mark Davies, Vocabulary Range and Text Coverage: Insights from the Forthcoming Routledge Frequency Dictionary of Spanish (2005).

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