Beyond age and intensive exposure: Initial proficiency effects on adolescents’ second language proficiency in an international school

This study investigates the effects of biological age and intensive exposure on L2 learning in an International School context as regards variability in learning rate and L2 development among pre- versus mid-adolescent learners. Longitudinal data collection at three time-points over one year involved semi-guided interviews and written productions among 28 L1-French learners of English in two age groups, either 11 years or 15 years of age. The data were investigated using quantitative measures of accuracy, fluency and holistic proficiency, and analysed with robust repeated measures ANOVAs and ANCOVAs. The findings suggest that the one-year intensive experience of English learning in the International School promoted significant gains in accuracy and holistic proficiency, but only one aspect of fluency, i.e., speech rate. When initial proficiency as Time 1 performance was controlled, the 15-year-old learners performed better than their younger peers only in written proficiency, while the 11-year-olds showed a faster learning rate in some aspects of oral accuracy and fluency. However, initial proficiency eclipsed age and exposure effects on L2 proficiency development during the one-year intensive experience. These results suggest that, for the introduction of short intensive programs in instructed contexts, learners’ initial proficiency and biological age should be considered. • A one-year intensive experience fosters adolescents' L2 accuracy and proficiency. • Initial proficiency trumps age and input in short intensive language programs. • Younger learners (age 11) show an L2 learning rate advantage over older adolescents.