Definition
Comprehensible input is language input that the learner can mostly understand, with the new material being just challenging enough to push acquisition.
Why it matters
Language is acquired most efficiently when learners can follow the meaning; input that is far above their level produces anxiety without acquisition, and input that is too easy produces no growth.
Scientific basis
Input hypothesis research (Krashen and successors) shows that acquisition happens most reliably when input sits at i+1 (just above the learner's current level).
How to apply it
- Choose reading and listening material where you understand 80–95% of the content.
- Use glosses and bilingual aids to keep meaning within reach while still encountering new forms.
- Gradually reduce support as comprehension strengthens.
Common mistakes
- Diving into native material far above current level.
- Avoiding input you cannot understand perfectly.
- Removing all aids, leaving only native content that produces frustration.
Examples
- A B1 Spanish learner reading graded readers before tackling Don Quixote.
- An A2 English learner watching captioned children's shows before moving to sitcoms.
Related concepts
- Immersion (is a foundation for)
Immersion is only effective when input is comprehensible. - Varied Practice (complements)
Varied input contexts strengthen the same structures through different forms.
Where it shows up
Domains: language-learning. Appears in the Language Learning cluster alongside 3 other concepts.
Source books
- Ultralearning: Scott Young
Articles that use this concept (1)
- Use Comprehensible Input to Learn a Language: comprehensible input