Improving Elementary Grade Students’ Science and Social Studies Vocabulary Knowledge Depth, Reading Comprehension, and Argumentative Writing: a Conceptual Replication

This conceptual replication study evaluates the effectiveness of the Model of Reading Engagement (MORE) content literacy intervention in improving elementary students’ vocabulary knowledge, reading, and writing outcomes across science and social studies. Using a cluster randomized controlled trial with more than 5,400 first- and second-grade students in 30 elementary schools, the study replicates earlier findings that MORE significantly strengthens domain-specific vocabulary knowledge depth and argumentative writing in both science and social studies. Students in MORE classrooms learned substantially more academic vocabulary—including both taught and untaught words—and demonstrated stronger ability to transfer knowledge to writing tasks that required claims, evidence, and reasoning. However, consistent with prior research, the intervention did not produce significant gains on domain-general reading comprehension measures, suggesting that such outcomes may require longer-term or multi-year exposure. Mediation analyses show that gains in vocabulary knowledge depth partially explain improvements in argumentative writing, highlighting vocabulary networks as a key mechanism for learning transfer. Overall, the study provides robust replicated evidence that content-rich literacy instruction can meaningfully improve students’ knowledge building and writing without narrowing instruction to basic skills alone.