The Zone of Comprehensible Input Is Razor Thin
In the list of ESL buzzwords frequently referenced by ESL professionals, comprehensible input (CI) is easily one the top three. The term comes from Steven Krashen’s Input Hypothesis, which states that language learners will make progress when they comprehend language input that is slightly more advanced than the language content that they currently know. Various versions of the following visual are frequently used to explain the concept.
I believe that this concept is a very important one for all second language teachers to understand.
Simply being “exposed” to a language does not mean that a person will learn something.
For example, it is commonplace to meet expatriates who have spent a decade or more living in China, who despite being exposed to spoken and written Mandarin Chinese on a daily basis, can’t speak and understand more than a dozen or so Chinese words.
What qualifies as comprehensible input, therefore, must be language content that the learner is actually able to comprehend based on what they already know. If the learner is unable to comprehend/understand the language content that they are being exposed to, then it falls into the “too challenging” category and does not qualify as comprehensible input.
The Zone of Comprehensible Input Is MUCH THINNER Than It Is Often Understood to Be
However, I believe that the above diagram does a disservice to language teachers (and language learners) by depicting the zone of comprehensible input as a large open space. Rather, I think the teachers should visualize the zone as shown below:
For beginners and most intermediate level learners of a second language, the actual area of comprehensible input is razor thin. While there is a lot of content that even complete beginners can immediately understand in a second language based on situational context and pre-existing knowledge, it represents only an incredibly tiny of fraction of the total input that the beginner could experience.
For example, for a beginner or intermediate level second language learner of Italian, listening to two speakers of Italian converse in Italian is going to generally result in the learner being exposed to zero comprehensible input.
Why?
In my estimate, to be able to make sense of any spoken sentence in a language, a listener will need to know and understand at least 60% to 80% of the words in the sentence. If the listener understands less than this, they may recognize some of the words they hear, but they simply will not have enough information to understand any of the words in the sentence that they have not yet learned.
On the other hand, if there are 12 words in a sentence and the listener knows/understands 10 of them, they might naturally understand the meaning of the other 2 words based on the context provided by the other 10.
For an upper-intermediate level or advanced level learner of Italian, listening to two Italian speakers converse or watching Italian language films may result in the learner being exposed to a significant amount of comprehensible input.
However, for an Italian language beginner (and probably for most intermediately level learners), at last 99% of conversations between two Italian speakers and most dialogue in Italian language films will not be comprehensible input. Aside from one word exchanges, like “hello” and “goodbye,” the learner will simply understand too few words of actual sentences to learn anything new from context.
What Is Suitable CI For Beginner/Intermediate Language Learners?
Because beginners and most intermediate level language learners don’t know/can’t understand enough words to experience comprehensible input based on linguist input alone, situational context is incredibly important. A language beginner’s ability to hear/see language content from the target language and understand/learn something new is dependant on their general pre-existing knowledge about the world.
For example, a Japanese 5-year-old participating in their first English-as-a-second-language lesson probably already knows the follow information:
Food can be purchased at restaurants.
Words can be used to order food in a restaurant.
If the teacher of that 5-year-old’s first English lesson introduces objects into the classroom environment that accurately resemble restaurant food and then demonstrates to the student(s) that saying “I want a hamburger” results in a hamburger being placed in their hands, the vast majority of 5-year-olds would very quickly understand that the phrase that they have been coached to say serves the purpose of ordering a hamburger.
They won’t yet understand any single word in the sentence they have been coached to say, but they do understand intuitively that the phrase as a whole can be used to order food.
There are a lot of aspects of ordering food at a restaurant in English, but for the Japanese 5-year-old in in this example who is studying English for the first time, the linguistic content for 99.9% of that content would be in the “too challenging zone.” If exposed to spoken linguistic content any more complex that what has been described in the above example, for the Japanese 5 year old, the content would simply go in one ear and out the other. Nothing would be understood, nothing would be learned, and nothing would be retained.
However, the content communicated in the above example is within that razor thin 0.1% of content from the topic of ordering food in a restaurant that a 5-year-old first-time English language learner could (and probably would) understand, learn, retain.
What Happens Next?
While the Japanese 5-year-old in our example may have entered the classroom only ready to understand the most basic comprehensible input, after observing and/or participating 3-4 times in the extremely basic food ordering interaction described above, something magical will occur.
The comprehensible input experienced by the learner will be integrated into their existing knowledge and they’ll now be ready for slightly more complex comprehensible input.
Now that the student understands that saying the phrase, “I want a hamburger” will result in being handed an object resembling a hamburger, the teacher can now demonstrate that the “ham” in “hamburger” can be replaced by the words “chicken” or "fish” to get different results.
Using objects that resemble both a chicken burger and fish burger, the teacher will be able to make it clear to the student(s) that placing a food item in the sentence pattern “I want a __________” will result in being handed the requested food item.
After the student(s) have absorbed this new information, the teacher will be able to continue to purposefully add new communicative elements one-by-one. As long as each new element (such as adding in the ability to request specific toppings on burgers or to also order fries, beverages, etc) is just slightly more advanced that what the student(s) have learned so far, the new learning will be readily, quickly, and easily absorbed.
Never Add More Than +1 Step of Complexity at a Time
If the teacher had began this lesson for a group of first-time English language learners by demonstrating a full-fledged fast-food restaurant role-play communication activity, the students would have immediately become confused, because the first set of content would have been too much for them to understand based on context.
But by beginning by simply showing the students how to request a hamburger in English, and then adding in one more slightly more complex food ordering element at a time, after 30 minutes, many 5-year-old first time English learners would already be able to productively participate in a basic restaurant role-play scenario.
Precisely Targeted Comprehensible Input Is A MUST
In my professional opinion, one of the most important responsibilities that second language teachers have, is to assess what their students already know and then come to classes prepared for a lesson that includes targeted comprehensible input that fits perfectly into the (often) razor-thin area that matches their students’ current ability/learning level.
If this is done correctly, their students will make consistent and steady progress in learning to use the target language to engage in productive communication in the real world.
If this is done incorrectly, the students could spend years going to language classes without ever actually gaining any ability to use the target language for communication purposes.