He is an American linguist and educational researcher.

Much of his recent research has involved the study of non-English and bilingual language acquisition.

Also called the Monitor Model (Krashen’s framework for SLA).

Developed in the late 1970s, widely accepted in the 1980s.

Most comprehensive SLA theory at the time.

According to Krashen 'learning' is less important than 'acquisition'

“Acquisition is the foundation of fluency.”

Acquisition:

• Like L1 acquisition

• Focus on communication, not grammar

Learning:

• Explicit grammar instruction

• Helps monitor accuracy

Implication:

• Balance both for fluency + accuracy

Language acquisition does not require extensive use of conscious grammatical rules and does not require tedious drill.

Acquisition requires meaningful interaction in the target language. - natural communication - in which speakers are concerned not with the form of their utterances but with the messages they are conveying and understanding.

Summary:

• Acquisition is key for fluency.

• Learning supports accuracy.

• Balanced approach is effective.

Crystal DavidThe Cambridge Encyclopedia of Language. Cambridge University Press, 1997.

Krashen, Stephen D. Principles and Practice in Second Language Acquisition. Prentice-Hall International, 1987.

Krashen, Stephen D. Second Language Acquisition and Second Language Learning. Prentice-Hall International, 1988.

Difference and Implication of Learning vs Acquisition

https://www.thehyperpolyglotactivist.com/book-online