Research and Reflections

Dual Immersion Instruction: The Promise of Equitable, Effective Instruction for English Learners

Research points to the benefits of dual immersion instruction

Although the United States has no official language, almost all American schools require students to learn in an English-only environment. English learners (ELs) are often confused with students who have learning disabilities, and their native language is considered an obstacle to overcome. English-centric schools fail to celebrate the benefits of bilingualism, including cognitive advantages, broader career opportunities, increased social and cultural opportunities, and a greater awareness and appreciation of the world. 

As educators strive to meet the educational needs of English learners in the age of the Common Core State Standards and test accountability, but are limited in terms of human and financial resources, decisions must be strategic and well-informed.  Certainly, the minimum goal–success for all students, for all programs designed to support ELs–has been defined by the Every Student Succeeds Act. Programs must be based on scientifically-based research; they must be well-implemented, evaluated, and revised on a regular basis. Thus, all programs must, at the very minimum, strive to promote English language proficiency and mastery of academic content among ELs. 

A few years ago, I conducted a study to examine the impact of dual immersion (DI) programs on student achievement. DI programs provide core content instructional delivery in both English and a target second language. I examined the achievement of students in two DI schools compared to the achievement of students in two traditional, English-only schools. The findings conclude that students in DI schools far outperformed their peers. 

Students at DI School A had a 10.9% higher ELA proficiency rate than students at Traditional School C. Also, students at DI School B had a 10.8% higher proficiency rate in ELA than students at Traditional School D. In addition, students at DI School A had a 7.8% higher math proficiency rate than students at Traditional School C. Finally, students at DI School B had a 12.9% higher math proficiency rate than students at Traditional School D.

Stephen Krashen, a notable language acquisition expert, asserts that children in DI programs perform as well or better than native speakers of English in five studies (Krashen, 2004). We now know that language acquisition involves a subconscious process. For instance, children acquire their first language without awareness of the fact that they are learning a language. They are, by all accounts, only aware that they are using a language for communication. The research suggests that linguistic input is derived from authentic settings and everyday modeling from authentic sources such as teachers, family, friends, and books. Applied to the education setting, this view suggests that unstructured classroom opportunities to enhance language acquisition are optimal (Peregoy & Boyle, 2008).

Studies have shown that individuals contain an internal grammar monitor. Krashen (1982) states that the single function of learning a language is that of developing a monitor to assume the correct usage of a langauge. This suggests that second language learners can apply rules of grammar when the following conditions are met: adequate wait time, conscious focus on form, and exposure to the rules of grammar. 

Research also informs us that rules of grammar are acquired in a predictable sequence. Language-proficient students are able to transfer skills to a second language with minimal difficulty. In fact, for many students, bilingualism is an asset when learning new grammatical structures. According to Peregoy and Boyle (2008), it is important to note that individual variances, including the influences of the primary language, can and do exist.

According to Krashen (1982), in order for linguistic input to be comprehensible, the input language, i.e., second language, should contain grammatical structures that are slightly more rigorous than the language acquirer’s current level of second language development. Peregoy and Boyle (2008) suggest that in order to comprehend challenging grammatical structures, students need to use context as a vital tool. Further, researchers recognize that speaking fluency cannot be directly taught but rather must emerge over time. 

The most influential variables supporting successful second language acquisition are a “low-anxiety learning environment, student motivation to learn the language, and self-confidence and self-esteem” (Peregoy & Boyle, 2008, p. 56). Achieving these goals is much more feasible in a DI environment than in an English-only model because the pedagogical goals of a DI program include creating a learning environment that is less stressful for non-native speakers of English. This is because students are not forced to adopt a target language until they are comfortable within their environment. 

The findings of my study conclude that integrated language learning in a dual-immersion program is the most equitable and best practice-oriented model based on long-term research on language acquisition. Not only can bilingual students succeed, they have the potential to outperform their monolingual peers. 


Krashen, S. (2004). The Acquisition of Academic English by Children in Two-Way Programs: What does the Research Say? Retrieved from file:///Users/kimsarfde/Desktop/krashendualimm.pdf

Krashen, S. (1982). Principles and Practice in Second Language Acquisition (Doctoral dissertation, University of Southern California). 

Peregoy, S. F., & Boyle, O. F. (2005). Reading, Writing, and Learning in ESL. (4th ed.). Boston: Pearson.

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About the Author: Dr. Kimberly Sarfde is a public school administrator. She spent the majority of her career working in urban schools before moving to a small town in New Hampshire. She is a four-time recipient of the Sontag Prize in Urban Education (2013-2016), which recognizes outstanding instruction and leadership in urban schools. She is also a teacher-leader fellow with the National Academy of Advanced Teacher Education (NAATE). She is a fierce proponent of bilingualism; her research documents the impact of two-way bilingual immersion programming on math and reading achievement for language minority and language majority students. As a former college dropout who worked at a gas station for seven years to support her four children, Kimberly understands the struggles many families face each day. One educator changed the trajectory of her life and inspired her passion for serving children.