The primary factor affecting language acquisition appears to be the input that the learner receives. Stephen Krashen took a very strong position on the importance of input, asserting that comprehensible input is all that is necessary for second-language acquisition.
Conversational interaction in a second language forms the basis for the development of language rather than being only a forum for practice of specific language features. (Gass, 2003)
Clipping is a handy way to collect important slides you want to go back to later.