Grant asked Diana for a definition of CI and she copied me in on her response to him. We actually had this discussion about three weeks ago here but nobody thought of looking to the creator of the term for a definition. Here is what Krashen said CI is in “Foreign Language Education, The Easy Way” and thank you Diana:
“Current language acquisition theory claims that we acquire language in only one way (italics are mine), when we understand messages, that it, when we obtain “comprehensible input”. Thus, we acquire when we understand what people tell us or what we read, when we are absorbed in the message. More precisely, we acquire when we understand messages contacting aspects of the language that we are developmentally ready to acquire but have not yet acquired.
“Teaching with CI means that we understand how vocabulary needs to be sheltered in order to make the language we are using and teaching in the classroom “comprehensible”. We want our students to understand the messages, to be absorbed in the message, thereby acquiring the vocabulary and structures we deem to be the best for gaining fluency. (My words here.) We choose to use the top 100-200 high frequency words for fluency because they are the most useful to us as teachers when teaching for acquisition.”
Krashen goes on:
“An aspect of the input hypothesis that is extremely important in discussing its application is that given enough comprehensible input, structures students are “ready” to acquire are invariably present in the input.
“Note that the actual relationship between the amount of CI obtained and individual progress depends on whether the CI contains aspects of the target language that the acquirer has not yet acquired, but is developmentally ready to acquire.
CI=I+1
“The +1 refers to the developmentally ready part of this statement.”