We love this study for what it says about great teachers. 

People generally agree that an effective English teacher may not make such a great Calculus teacher, or vice versa. While people may assume that good teaching probably won't translate across subjects, few have considered whether good teaching can translate across all students.

New research asks this very question, looking specifically at whether teachers who have high scores on value-added measures (VAM) with non-English learner (EL) students have similarly high VAM scores with EL students. The study, by Susanna Loeb, James Soland and Lindsay Fox, finds that, yes, good teaching for one group of students remains effective for another group with different needs in the same class.

Examining seven years of data from teachers who had both EL and non-EL students, the researchers found that consistency in effective teaching holds true for both math and reading, although the relationship is stronger with effective math teachers. More than half of the teachers considered to be in the top-fifth of all teachers for non-EL students are also in the top fifth for EL students. For reading, this overlap is slightly lower: a little under half of the top teachers for non-ELs are also the top teachers for ELs.

A few characteristics, however, are associated with teachers being more effective with EL students. Specifically, teachers who have a bilingual certification or are fluent in Spanish tend to be more effective with their EL students relative to their non-EL students.

The implication for those hiring new teachers is that their best option is to find a good teacher – period. However, if the school system has lots of EL students, finding a good teacher who is also fluent in Spanish (assuming that's the language commonly