This input hypothesis suggests that language acquisition occurs when learners receive messages that they can understand, a concept also known as comprehensible input. However, Krashen also suggests that this comprehensible input should be one step beyond the learner’s current language ability, represented as i + 1, in order to allow learners to continue to progress with their language development.
This is highlights the importance of using the Target Language in the classroom. The goal of any language program is for learners to be able to communicate effectively. By providing as much comprehensible input as possible, especially in situations when learners are not exposed to the TL outside of the classroom, the teacher is able to create a more effective opportunity for language acquisition.