Revising expectations: the effect of different levels of CLIL exposure on young learners' oral performance

Research evidence predominantly based on studies with older learners suggests that Content and Language Integrated Learning (CLIL) instruction yields significant language gains when exposure exceeds 300 hours (Muñoz, 2015). However, the impact of high-intensity CLIL on young learners' oral proficiency remains underexplored. This study examined fluency, pronunciation, and productive vocabulary measures in young L1-Spanish learners (mean age = 10.46) across four groups: non-CLIL (n = 23), low-CLIL (n = 21), high-CLIL (n = 32), and a younger high-CLIL group (n = 32; mean age = 9.84) with 0, 707, 2473, and 2164 CLIL hours, respectively. Socioeconomic status and extramural exposure were controlled. Intraclass correlations, Kruskal-Wallis, post-hoc, and Friedman tests were conducted. Significant advantages were limited to both high-CLIL groups over the non-CLIL group at the vocabulary level, providing policymakers with empirical evidence about the markedly different outcomes of high, and low-CLIL programmes in relation to oral gains with young learners.