Adolescent language minority students’ vocabulary growth: Exploring heterogeneity with multilevel analysis

Three studies within this dissertation aim to provide insight on differential vocabulary growth trajectories of adolescent language minority students across two years and examine how they respond to a research-based academic vocabulary intervention, Word Generation. In all three studies, the language minority student sample included initially fluent English proficient (IFEP), redesignated fluent English proficient (RFEP), and limited English proficient (LEP) students. In Study 1, I investigated general vocabulary and academic vocabulary growth trajectories of sixth- to eighth-grade English-only and language minority students using an individual growth modeling analysis. Students were assessed at four time points on a standardized measure of general vocabulary and a researcher-developed academic vocabulary test. On both vocabulary measures, IFEP students slightly outperformed English-only students on average, and English-only students scored higher than RFEP and LEP students at baseline. Although there were differences in the general vocabulary growth trajectories across groups, there were greater group differences in academic vocabulary growth. English-only students did not improve as much across the study. In Study 2, I examined general vocabulary, academic vocabulary, and reading comprehension growth trajectories of adolescent RFEP students using an individual growth modeling analysis. Students completed up to four waves of reading-related measures during a two-year time period. Findings indicate that students’ scores on the vocabulary and reading measures were positively correlated with their years since redesignation and students showed growth over time on average on all outcomes. The rate of growth did not differ by years since redesignation. In Study 3, I investigated the longitudinal effects of an academic language intervention, Word Generation, on adolescent English-only and language minority students’ word learning. Thirteen middle schools from an urban district in California were randomized to treatment and control conditions. Using individual growth modeling, I found main effect of treatment on students’ academic vocabulary knowledge. In addition, students in the treatment condition maintained the improvement in their vocabulary knowledge in the follow-up year. Findings from this dissertation underscore that language minority students represent a heterogeneous group of students with varying configurations of English language proficiency. They also indicate that both English-only and language minority students can benefit from an academic language intervention