Theme-Based, Sheltered, or Adjunct? Evaluating CBI Models for Improving English Reading Skills in Chinese EFL Classrooms

Content-Based Instruction (CBI) has been widely promoted as an effective approach for integrating language development with subject matter learning in English as a Foreign Language contexts. However, limited empirical evidence exists comparing the effects of different CBI models on students' reading proficiency, particularly within Chinese tertiary education. Existing studies often focus on general outcomes or perceptions, leaving a gap in understanding how specific instructional models influence distinct reading sub-skills. This study aimed to address this gap by comparing the effectiveness of three CBI models (theme-based, adjunct, and sheltered) on university students' English reading proficiency, focusing on three sub-skills- understanding explicit information, understanding implicit information, and using linguistic features to understand texts. Employing a mixed-methods design, the study involved 105 Chinese university students across three intact classes, with quantitative data collected from the English reading pretest and posttest and qualitative data collected from classroom observations and semi-structured interviews. Quantitative results indicated that while all groups improved significantly from pretest to posttest, the theme-based model led to significantly higher gains in total reading scores and in the ability to use linguistic cues. Qualitative findings suggested that the instructional design, input organization, and opportunities for textual scaffolding varied across models and contributed to the outcomes. These findings offer practical implications for EFL curriculum planners and educators seeking to align reading instruction with model-specific strengths for more effective literacy development.