Document Type



Doctor of Philosophy



Date of Defense


Graduate Advisor

Kim H. Song


Natalie Bolton

Cody Ding

Gloria Delany-Barmann


K-12 ELs in the U.S. are increasing in number and diversity (Park, et al., 2018), requiring schools to establish and grow language instruction education programs (LIEPs) that facilitate language acquisition for a wide range of learners, while also providing equitable opportunities to learn. The study used a quantitative, pretest-posttest, research design to address gaps in the literature noted by Takanishi & Menestrel (2017), regarding which LIEPs are most effective for various EL subgroups, and to explore the effects of Coteaching for ELs (COTEL) on growth in proficiency. Data from 723 ELs in two Midwestern districts was disaggregated three ways to determine if ELs of various home languages, grade levels, and starting proficiency levels grew more in COTEL or in other kinds of English instructed LIEPS (NO COTEL). Growth was calculated using ACCESS test scores from 2018 and 2019 to avoid pandemic effects. Several two-way analyses of covariance (ANCOVA) were conducted to control for pretest differences and to better isolate the effects of COTEL on growth in English amongst various subgroups.

Results showed that overall ELs grew more in COTEL. Additionally, statistically significant, higher growth was discovered for 4th and 7th graders in COTEL, and for ELs with Developing (DEV) and Expanding (EXP) starting proficiency levels in Grades 3-5, and for all starting proficiency levels in Grades 6-8. Of particular interest, speakers of 33 lower incidence languages (MIX33) accelerated their growth in English in COTEL, while floundering in other kinds of English-instructed LIEPs (NO COTEL). Based on these findings, the researcher proposes that among English-instructed LIEPs, COTEL holds the most promise for implementing research-based practices with fidelity, for infusing a translanguaging stance, and for building the capacity of each classroom’s teachers to succeed with multilingual learners.