Bilingual programs that provide initial instruction in DLLs’ native language in order to develop their English skills are considered “subtractive” in that they are not designed to support or enhance DLLs’ first language abilities. Transitional bilingual education (TBE)—also known as early-exit bilingual programs, integrated TBE, and developmental bilingual education, also known as late-exit bilingual programs, are the main types of subtractive bilingual program models.
Transitional Bilingual Education
Transitional bilingual education is the most common bilingual model for DLLs in the U.S. For instance, it is the state-mandated instructional model in Texas, where approximately one out of every six U.S. DLLs lives. Under this model, children’s native language is used for an initial period of time to build basic literacy and content knowledge, but then they are rapidly transitioned to English. A critique of TBE programs is that they typically segregate DLLs from native English-speaking peers, which can isolate them from language-rich interactions present in linguistically-integrated classes.
Integrated TBE programs counteract the segregation in TBE programs by incorporating DLLs into English classrooms for a portion of the school day.
Developmental Bilingual Education
Under the developmental bilingual education (DBE) model, students’ native language is used to build basic literacy and content knowledge for a longer period of time than under the TBE model. It also provides a higher initial proportion of native language instruction than TBE provides. In some versions of the model, the proportion of initial instruction in the native language versus English is 90:10. The proportion is gradually reduced as students become more proficient in English. The goal of the model is for students to develop biliteracy while being able to access academic content in English.