Research on writing development in content and language integrated learning (CLIL) settings is still inconclusive. This study intends to make a contribution in this respect by presenting longitudinal findings on the development of written complexity, accuracy and fluency (CAF) in secondary education CLIL and non-CLIL learners. Participants in the study (N = 50) are a group of CLIL students (N = 30) learning science or social science through the medium of English and a group of comparable non-CLIL learners (N = 20) of English. Analytical CAF measures are used to investigate their performance in a written composition at four data collection times over three years. Within-group results show significant differences in the scores obtained in most of the CAF measures for CLIL learners at the different data collection times, compared to significant differences only in lexical complexity and accuracy for non-CLIL participants. Results of between-group comparisons controlling the hours of exposure are mixed: non-CLIL students progress significantly more in lexical complexity than their CLIL peers, although the latter tend to obtain higher scores overall. In sum, evidence suggesting the greater effectiveness of the CLIL approach is found.
IntroductionLanguage is one of the five dimensions of the content and language integrated learning (CLIL) approach -along with culture, environment, content and learning (Marsh, Maljers and Hartiala 2001) -and the one that has attracted most research interest in CLIL literature. This is probably due to the fact that the most common reason to introduce CLIL is to improve overall foreign language competence (Ruiz de Zarobe 2010), without having to devote extra time to the teaching of the target language.Research in CLIL has gathered force over the last decade and many studies regarding the impact of CLIL on language development have shown positive findings, despite a few critical voices (e.g. Bruton 2013). However, some areas of language competence have received more attention than others. In particular, the role of writing in CLIL contexts has been largely unrecognised (Llinares, Morton and Whittaker 2012). In fact, an overview study on CLIL learning outcomes conducted by Dalton-Puffer (2008) classified writing as one of the areas of linguistic competence likely to remain unaffected by CLIL instruction.