Fact · Languages and accents
Krashen's input hypothesis says learners progress when they understand input that is slightly more advanced than their current level, which he called i+1.
Checked against its source on October 17, 2026
In the source's own words
“This states that learners progress in their knowledge of the language when they comprehend language input that is slightly more advanced than their current level.”
Input hypothesis, Wikipedia contributors, Wikipedia, n.d., Overview, input hypothesis.
Open the original- What it measures
- Krashen proposed five hypotheses; this is the one about comprehensible input.
- What it does not show
- An encyclopedia summary. The notion of i+1 is theoretical and critics say its values are vague.