useful in this regard is the second-language acquisition theory of Stephen. D. Krashen which ... Central to Krashen's theory of second-language acquisition is his.
Introduction The influence of Stephen Krashen on language education research and practice is undeniable. First introduced over 20 years ago, his theories are still debated today. In 1983, he published The Natural Approach with Tracy Terrell, which combined a comprehensive second language acquisition theory with a curriculum for language classrooms. The influence of Natural Approach can be seen especially in current EFL textbooks and teachers resource books such as The Lexical Approach (Lewis, 1993).
Bracey Schools Matter's Professor Stephen Krashen has been a long time critic of the media promulgated mythology that there's a shortage of qualified workers, particularly those in the Science Technology Engineering Math (STEM) fields.
Stephen Krashen's Theory of Second Language Acquisition it explains that:
"Language acquisition does not require extensive use of conscious grammatical rules, and does not require tedious drill."
this site talks about three things that could be useful for us
1.the relationship of theory to practice, 2. second language acquisition theory 3. providing input for acquisition
it is a very useful site it explains about two theories that had a large impact on all areas of second language research and teaching "Monitor Theory" and "Interlanguage Theory"