Why do I continue to correct their grammar? I consider it a form of Comprehensible Input. It is a feedback of their own sentence. I believe they will NOT benefit in a conscious grammar rule way: "Oh, right! Grammar rule #27: Pronouns of gender. Females = she & her, Males = he & his." Krashen brought this out very clearly in his description of learning French which I published previously.
But students will benefit from experiencing an extensive amount of correct Comprehensible English Input at a level of i+1 as explained by Krashen:
"Language acquisition is very similar to the process children use in acquiring first and second languages. It 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. Error correction and explicit teaching of rules are not relevant to language acquisition (Brown and Hanlon, 1970; Brown, Cazden, and Bellugi, 1973), but caretakers and native speakers can modify their utterances addressed to acquirers to help them understand, and these modifications are thought to help the acquisition process (Snow and Ferguson, 1977). It has been hypothesized that there is a fairly stable order of acquisition of structures in language acquisition, that is, one can see clear similarities across acquirers as to which structures tend to be acquired early and which tend to be acquired late (Brown, 1973; Dulay and Burt, 1975). Acquirers need not have a conscious awareness of the "rules" they possess, and may selfcorrect only on the basis of a 'feel' for grammaticality."
And despite what the calculator punchers say (as one teacher said to me about acquisition through Comprehensible Input, "the number of YEARS required is going to be well into the triple digits. Your student's great-great-grandchildren will all be retired before your students will have acquired the ability to write like a 15-year-old"), students actually can learn to an intermediate level in two years if they have wife of that language (as did Guy Brook-Hart and Mert Bland) or sufficient alternative input.