Introduction

The field of foreign/second language (L2) learning has undergone important changes in recent years, due to the urgent need to respond to growingly dynamic multilingual societies in a globalised world. In Europe, this need has led educational authorities to find new and more effective ways of teaching foreign languages to guarantee multilingual/multicultural citizenship. In order to achieve this goal, two major new trends in foreign language teaching are gradually being implemented in schools: the teaching of foreign languages at an early age and the integrated teaching of foreign languages and other academic disciplines (Content and Language Integrated Learning [CLIL]). Far from being separate models, these two educational trends are brought together in big-scale programmes which are currently being implemented in some European countries, like Spain. However, in spite of the growing spread of CLIL educational models at primary school level, research on CLIL young learners' language development is clearly underexplored when compared to studies at secondary and even tertiary levels. This is clearly the case in CLIL classroom interaction research (see Nikula et al., 2013), where only a few studies have been conducted at primary level, either using formal (e.g. García Mayo & Lázaro Ibarrola, 2015; Serra, 2007) or functional perspectives (e.g. Pastrana, 2010) on language learning. More studies are then necessary on CLIL at primary level, especially those focusing on content and language integration, which are practically absent in the primary CLIL research scenario.

The importance of addressing content and language integration in CLIL/immersion research has been reported in recent studies. Cenoz et al. (2014) have emphasised the need for classroom-based research that focuses not only on the acquisition of the foreign language but also on how students use and learn this language for creating (and learning) academic content; in other words, how language and content are learned in integration. The concept of integration in CLIL can encompass different levels or perspectives: integration at the level of the curriculum, participants' (teachers, students, etc.) perceptions on integration or integration at the level of classroom practices.