Comprehensible input

Though there are many theories as to how we acquire language, both first and second, one of the most prominent modern theories in the field of Second Language Acquisition (SLA) is the Comprehensible Input Hypothesis, developed by Stephen Krashen. This theory was originally called the "Input Hypothesis."

According to Krashen, we acquire language "only" when we receive comprehensible input (CI). This hypothesis claims that we move from "i" to "i+1" by understanding input that contains "i+1". In this equation, "i" represents previously acquired linguistic competence and extra-linguistic knowledge. Extra-linguistic knowledge includes our knowledge of the world and of the situation- that is, the context. The "+1" represents new knowledge or language structures that we should be ready to acquireKrashen, S. (2003). "Explorations in Language Acquisition and Use". Portsmouth: Heinemann.]

The Comprehensible Input hypothesis can be restated in terms of the natural order hypothesis. For example, if we acquire the rules of language in a linear order (1, 2, 3...), then "i" represents the last rule or language form learned, and "i+1" is the next structure that should be learned [Seek information on the acquisition-learning hypothesis to learn more about the differentiations between learning and acquisition] . It must be stressed however, that just any input is not sufficient, the input received must be comprehensible. According to Krashen, there are three corollaries to his theory.

Corollaries of the Input/Comprehension Hypothesis

# "Talking (output) is not practicing"
Krashen stresses yet again that speaking in the target language does not result in language acquisition. Although speaking can indirectly assist in language acquisition, the ability to speak is not the cause of language learning or acquisition. Instead, comprehensible output is the result of language acquisition. [See comprehensible output for more information on output theories and hypotheses]

# "When enough comprehensible input is provided, i+1 is present"
That is to say, that if language models and teachers provide enough comprehensible input, then the structures that acquirers are ready to learn will be present in that input. According to Krashen, this is a better method of developing grammatical accuracy than direct grammar teaching.

# "The teaching order is not based on the natural order"
Instead, students will acquire the language in a natural order by receiving comprehensible input.

Applications in Second Language Teaching

The Beginning Level

* Class time is filled with comprehensible oral input
* Teachers must modify their speech so that it is comprehensible
* Demands for speaking (output) are low; students are not forced to speak until ready
* Grammar is only included for students high school age and older

The Intermediate Level

* Sheltered subject-matter teaching that uses modified academic texts to provide comprehensible input.
* Sheltered subject matter teaching is not for beginners or native speakers of the target language.
* In sheltered instruction classes, the focus is on the meaning, and not the form.