The purpose of this article is to examine the practical work that participants in a second language (L2) classroom are doing in the course of their actions. These actions are observed through the accounts produced by members, which in turn represent their rationalities, or ethno-methods (Garfinkel, 2002), that are in use during the ongoing sequence of utterances. Based on the extracts presented for analysis, this article concentrates on how participants produce and recognise the context in which they are in, and to which they orient their work; and how this context becomes an inspectable phenomenon of inquiry through ethno-methods, such as the invocation of membership categories ('teacher' and 'student') produced along the course of the interaction. The materials on which I shall focus my discussions were gathered from a first grade Portuguese as an L2 classroom in a primary school in Macau, China. The results indicated an ongoing production of categorial aspects that enabled participants to have no problems in following the sequential organisation of the talk and other conduct in a way that it was 'just enough' to make L2 lesson events happen.