Effects of Tier 1 Content Literacy Intervention on Early-Grade English Learners’ Reading and Writing: Exploring the Mediating Roles of Domain-Specific Vocabulary and Oral Language Proficiency

Abstract

This exploratory follow-up study to a randomized controlled trial examined (a) the differential impact of classroom-based (Tier 1) content literacy intervention on reading and argumentative writing outcomes among Grades 1 and 2 English learners (ELs; n = 1,236) and their Englishproficient peers (EPs; n = 4,161) and (b) the mechanisms determining how the intervention yielded effects on ELs. The study was conducted across 30 elementary schools in an urban U.S. school district. The 10-week intervention, comprised of 20 lessons in science and social studies thematic units, was delivered by classroom teachers. The core components were designed to build students’ content and vocabulary knowledge through informational texts and concept mapping and to transfer their schema to argumentative writing and research collaboration. Results show that while the intervention did not significantly improve reading proficiency (effect size [ES] = .01 for ELs and ES = -.02 for EPs) and basic literacy skills (ES = .04 for ELs and ES = -.02 for EPs), it significantly bolstered argumentative writing in science (ES = .25 for ELs and ES = .24 for EPs) and social studies (ES = .42 for ELs and ES = .44 for EPs). The treatment effect on reading proficiency among ELs was fully mediated by their improved domain-specific vocabulary knowledge and English oral proficiency. A significant indirect effect on social studies argumentative writing through domain-specific vocabulary knowledge was also evident. These findings corroborate the effectiveness of the content literacy intervention, providing insights into for whom and how the intervention was effective.