Language learning and youth study

Scientists have long posited that there is a "critical period" for language learning, but new research suggests that the time frame stretches on much longer than previously thought. The study suggests that children remain skilled at learning the grammar of English up to the age of 17 or 18. The study also found that it is difficult for people to achieve proficiency in English similar to that of a native speaker unless they start learning a language much earlier, by the age of 10. People who start learning a language between the ages of 10 and 18 will still learn quickly, but since they have a shorter window before their learning ability declines, they're less likely to reach the proficiency of native speakers, the researchers found.
Hartshorne, J. K., Tenenbaum, J. B., & Pinker, S. (2018). A critical period for second language acquisition: evidence from 2/3 million English speakers. Cognition, 177, 263-277. http://l3atbc-public.s3.amazonaws.com/pub_pdfs/JK_Hartshorne_JB_Tenenbaum_S_Pinker_2018.pdf

Benefits of Reading Aloud on Language Acquisition

Findings from this study show the positive effects of read-alouds and storytelling on literacy development and second-language acquisition, which have also been confirmed many times in the research literature. In addition, there is consistent evidence that in-school free voluntary reading (sustained silent reading) is effective for both first- and second-language acquisition. Hearing stories stimulates interest in particular books, which in turn encourages a reading habit. In this study, the authors investigate the effect of a combination read-aloud/self-selected reading experience on sixth graders in Korea studying English as a foreign language on measures of both language/literacy development and interest in reading. The study states that the latter may be the most important measure, as it is an indication of whether the students will continue to read on their own and thereby continue to improve in English after the program ends.

Cho, K. S., & Choi, D. S. (2008). Are read-alouds and free reading “natural partners”?: An experimental study. Knowledge Quest, 36(5), 69-73. https://eric.ed.gov/?id=EJ822222