The focus of this paper will be placed upon the methods people use to interact in second language learning settings, discussing interactional aspects of language use in the ongoing production of classroom events. The extracts selected for analysis were drawn from Portuguese language lessons (for beginner and advanced students) in a Chinese university. The results show how L2 classroom participants secure joint orientation and mutual understanding of the categorial pairs (such as 'teacher-student' and 'native-non-native') being invoked in the sequential organization of the utterances. In other words, when classroom members show orientation to a categorial pair, their subsequent moves will exhibit predicates (actions) of that pair, which will be available to the analyst as phenomena to be explored. This suggests that the sequential elements of the interaction and the membership categorization work carried out by the participants require attention for praxiological enquiries.