Scientific Literacy Deficits, Vocabulary Barriers, and Evidence-Based Intervention Models in 21st-Century Science Education

Abstract

Abstract Scientific literacy has become an indispensable competency for informed citizenship, evidence-based decision-making, and participation in a science- and technology-driven world. Yet persistent deficits in scientific literacy remain a critical global challenge, with PISA 2022 data indicating that approximately one in four 15-year-olds across OECD countries fails to meet baseline scientific proficiency. At the core of this challenge lies a linguistic problem: the specialized academic register of science imposes language demands that many learners, particularly multilingual students and those from socioeconomically disadvantaged backgrounds, are structurally underprepared to meet. Despite growing recognition that academic vocabulary knowledge functions as a primary mediator of scientific understanding, instructional responses in many classrooms remain inconsistent and insufficient. This narrative review synthesizes current literature across four interconnected dimensions: the evolving definition of scientific literacy in the 21st century; the global imperatives and documented deficits; the lexical and vocabulary barriers that structurally obstruct science learning; and nine empirically tested intervention models designed to address these barriers. Interventions examined include literacy-science integrated programs, generative vocabulary strategies, morphological awareness instruction, explicit vocabulary approaches, teacher professional development models, and scaffolded support in multilingual English-medium instruction settings. Findings consistently demonstrate that deliberate vocabulary instruction yields measurable gains in science vocabulary knowledge, conceptual understanding, and scientific argumentation across diverse educational contexts.