On average, it took the students 3.8 years to reach English proficiency. But over the course of the study, almost 20 percent of students did not score high enough on the state exam to be reclassified.
This is such a big question in education these days; how long does it take learners to become proficient in a new language through schooling? Most often, children are “graduated” from language support (where available) in a year or two. Very few schools can implement the 3-9 years of language support needed to ensure all children reach proficiency in the school language. This small-scale study in the US shows that learners took, on average, 3.8 years to reach proficiency, living in an English-speaking environment. We could extrapolate from this to presume that learners living in environments where the school language is not supported outside school (in international contexts) would need more time and support. How does your school, or your child’s school, measure up?
How Long Does It Take ELLs to Develop English Proficiency? – Learning the Language – Education Week.