Two studies find mixed results on grouping English learners ^{CEFR B2}

Two recent studies examined the academic effects of grouping English learners (ELs) together in school classes. The high school analysis, reported in the Peabody Journal of Education, used New York City Public School data for 31,303 ninth graders from 2013, 2014 and 2015. Researchers categorized students by years learning English before ninth grade—newcomer EL (1–3 years), developing EL (4–6 years) and long-term EL (7 or more years)—and measured the percent of ELs in each student's courses. They compared outcomes across high schools with EL populations of 50% or more and those with less than 50%.

The high school study found that higher concentrations of ELs in courses were associated with lower chances of graduating and lower college enrollment, regardless of prior years learning English or the overall school share. Specific reported differences included a 10–15% lower likelihood of four-year graduation, 6–11% lower six-year graduation, 12–13% lower immediate college enrollment and 9–13% lower college enrollment within 2.5 years.

A separate randomized trial in elementary schools assigned 84 fourth- and fifth-grade ELs to small groups that were either all ELs or mixed with non-EL peers. All groups received the same 12-week language and literacy curriculum taught by the same teachers. The trial measured language skills, reading comprehension and argumentative writing and recorded how teachers implemented lessons. On average, the study found no statistically significant differences in academic outcomes between homogeneous and heterogeneous groups, but heterogeneous groups tended to benefit students with higher English skills while homogeneous groups helped those at earlier stages. Classroom observations showed more open-ended questioning and richer discussion in heterogeneous groups, and more targeted language instruction in homogeneous groups.

Both research teams conclude that grouping ELs together should not be a default practice; they advise caution and more targeted use of separate EL courses. Funding for the studies came from The Institute of Education Sciences and the US Department of Education.