I just reviewed an interesting article regarding new instructional strategies to promote greater academic success among students not yet proficient in English. The strategies are being employed in Fresno, CA. Essentially, they get students talking to each other in pairs, rather than just listening to the teacher. It works because the students are interacting (actually practicing) with the language. Fresno was ahead of the state in helping students become English proficient last year, with 18 percent achieving that goal in the district, compared to 11 percent statewide.
https://edsource.org/2016/new-teaching-techniques-designed-to-help-english-learners-succeed/566317
This article reminds me of a strategy employed in several Ascend Math schools with ELL learners. All the instructional content in Ascend Math is captioned in Spanish. However, teachers have told us that their Spanish speaking students like to put the English captions on to help them learn English while learning math. Then, they speak along with the video instructor, practicing their English while learning math.