As a result of the migratory waves of the end of last century the sociolinguistic situation in some schools in Barcelona is complex because their students have very diverse origins and they followed particular linguistic trajectories. In these institutions language teaching is organized separately: on one hand, Catalan is the language used in all the subjects of the curriculum, except in the Spanish, English and French classes. On the other hand, the reception classroom is constructed as a space of multilingual practices, similar to the real linguistic practices of the students. This article aims to analyse and contrast, using ethnographic audio and video data, the conceptions underlying the above mentioned teaching spaces in a secondary school in Barcelona.