Teachers and students at the crossroads: unpacking L1 use in CLIL in China’s higher education

Grounded in the concept of translanguaging, the use of first language (L1) in foreign language (L2) classrooms has sparked considerable debate within Content and Language Integrated Learning (CLIL), particularly in under-researched non-Western contexts such as China. A significant research gap remains regarding the contexts, purposes, and factors influencing L1 use. This qualitative study, situated within English language education in Chinese higher education, addresses this gap with a focus on one purposively selected CLIL classroom. Conversation analysis of classroom observations indicates that translanguaging functions as a strategic, context-driven choice shaped by teacher awareness and learner agency rather than as a fallback to L1. In-depth interviews with the teacher and students reveal that L1 use, framed within Cultural-Historical Activity Theory, is mediated by physical and conceptual tools and peer interactions, with effects observed both inside and outside the classroom. The study also highlights how the division of labour and institutional, educational, or ideological rules shape the balance between L1 and L2 use and create tensions between traditional L2 immersion expectations and learners' practical needs. These findings call for a more nuanced understanding of translanguaging and suggest the reconsideration of strict L2-only policies to enhance learner engagement and comprehension in CLIL.