Around one in five American students currently speaks a language other than English at home, and Census projections estimate that this number will continue to rise in the coming decades. These multilingual children are commonly known as “dual language learners” (DLLs), since they generally begin learning English while they are still working towards basic proficiency in their home language. The growth in this demographic is most dramatic in the early years—nearly one in three Head Start participants is a DLL.
In the PreK-12 years, federal law requires schools to provide these students with language instructional services. This additional support can take one of two forms: English as a Second Language (ESL) or bilingual programming. Within these two categories, there is a large variety of model types. In recent years, a growing body of research suggests that instructional models that incorporate a DLL’s home language leads to higher academic achievement than English-only approaches. Several state and district leaders have also pushed to ensure that all mainstream teachers—in addition to DLL specialists—use best practices to support DLLs in their classrooms.Beyond instructional considerations, part of the challenge in better serving DLLs lies in appropriately identifying, assessing and exiting them from services when they reach English proficiency. In particular, it can be difficult to develop fair, valid testing and accountability policies since many factors influence the unique developmental trajectory a DLL takes to acquire English. Moreover, there is large variability in how states track their DLLs’ English language and academic progress due to differences in assessments, cut scores and data reporting. This leads to a lack of clarity on how DLLs are performing over time and across state lines.