See here an enlightening video by Krashen about comprehensible input
A simple example of how the mother tongue can be used to make input comprehensible is the student who reads about the in her native language before listening to a lecture on the topic in class or reading about it in her history textbook. It is helpful if teachers regularly encourage students to make use of this strategy.
Language Learning and Teaching: Krashen's Input Hypothesis
Subsequent critiques of Krashen have focused more on the pedagogical implications of his theories, for example his claim that comprehensible input is a sufficient condition for language acquisition. Critics, e.g., Swain (1985), counter that the production of language (output) is a necessary condition for language development.
The input hypothesis was first published in 1977.
Krashen claimed that linguistic competence is only advanced when language is subconsciously acquired, and that conscious learning cannot be used as a source of spontaneous language production.
THE ROLES OF MOTIVATION AND COMPREHENSIBLE INPUT …
Extensive voluntary reading provides non-native students with large doses of comprehensible input with a low affective filter, and thus is a major factor in their general language acquisition.
comprehensible input Archives - Page 2 of 2 - …
Secondly, ESL students are often anxious in mainstream classes. Teachers should seek ways to reduce the students' affective filter in order that they can profit from the comprehensible input they receive.
The distinction between input and comprehension is clearly vital.
A further criticism of Krashen's theories is levelled at his repudiation of grammar instruction. Critics claim that some kind of direct focus on grammar is both beneficial and necessary - see Long (1998). Krashen (2003), after a comprehensive analysis of the research data in these two areas, concludes that neither learner output nor grammar focus have any direct influence on acquisition. He states that his hypotheses " .. have not only survived well over the years but have also proven to be useful in other areas of language education. So far, research results remain consistent with these hypotheses and there is no counterevidence."
after participation in comprehension-based language activities
Krashen is a strong advocate of the whole language approach to the teaching of reading, and has written many articles in support of it. In essence, whole language proponents claim that children learn to read most enjoyably and efficiently by exposure to interesting stories that are made comprehensible to them through pictures and discussions. This is in contrast to structured decoding programmes (usually designated ) in which children learn to read by sounding out the various parts of words.
The Case for Comprehensible Input - Language Magazine
Learners with a low affective filter will not only be efficient language acquirers of the comprehensible input they receive. They are also more likely to interact with others, unembarrassed by making mistakes for example, and thus increase the amount of that input.