According to the literature on second language acquisition, what are the conditions for successful extensive reading? Does the literature provide any suggestions on how many words a learner should read and on how long it takes to see benefits of extensive reading?
According to Krashen's Input Hypothesis, the main conditions for successful extensive reading are:
- abundant input
- comprehensible input
- input is slightly above current level of understanding
There is no particular guidance on how many words you should read. Since it's "extensive", you should just read as much as you possibly can while still enjoying yourself enough to not burn out. That said, a native speaker of English knows roughly 10,000-30,000 word families, depending on her/his level of education, but possibly less than 10,000 word families are necessary to read profitably.