Quality of instruction is more important than the language used

A review published in Review of Educational Research synthesizes research on English reading outcomes for Spanish-dominant English language learners (ELLs) in elementary schools. The review is in two parts. The first looks at studies of language of instruction, while the second reviews reading approaches for ELLs while keeping the language of instruction constant. A total of 13 studies met the inclusion criteria for language of instruction. While the overall findings indicate a positive effect (effect size = .21) for bilingual education, the largest and longest evaluations found that, by the end of elementary school, there was no difference in outcomes for those children who were taught in Spanish and transitioned to English or who were taught only in English. 

The review also identified whole-school and whole-class interventions with good evidence of effectiveness for ELLs. These include Success for All, cooperative learning, Direct Instruction, and ELLA. There were also positive effects for struggling ELL readers from those programs that use phonetic small-group or one-to-one tutoring. The most promising interventions share the use of extensive professional development, coaching, and cooperative learning. The findings support a conclusion that the quality of instruction is more important than the language of instruction.