Programs that aim to educate students to be bilingual and biliterate are considered “additive” bilingual models. Examples of these programs include heritage language (also called maintenance bilingual or late-exit bilingual), two-way immersion (also called dual immersion), and one-way immersion programs.
Heritage Language Programs
DLLs in heritage language (HL) programs often take a class — separate from their other subjects — in their native language. HL programs are often found in communities at-risk of losing a minority language and for this reason are common models for Native American language instruction.
Two-way Immersion Programs
DLLs in two-way immersion (TWI) programs learn content in both English and their native language. Most TWI programs strive to maintain a student population that is 50 percent DLLs and 50 percent students who speak English at home. TWI students usually spend 50 percent of their time in each language. This can be achieved by splitting up the day’s subjects (and/or minutes) into each language, alternating language days, or switching languages each week. Presently, most TWI programs in the U.S. serve Spanish-speaking DLLs, however, French and Chinese programs are on the rise. The Center for Applied Linguistics maintains a database of TWI programs in the U.S. At this time there are 458 records in the database, 425 of which are English-Spanish programs.
One-way Immersion Programs
Like in TWI programs, DLLs in one-way immersion programs spend half of their time learning academic content in English and the other half learning content in their native language. However, as opposed to TWI programs, all students in one-way programs are DLLs from the same home language group.