Sian's taking up of the position of domestique is not simply a female version of Group A membership: Black notes that this role is also assigned occasionally to boys in the group. However, these boys also participated in more prolonged exchanges, whereas this was not the case for Sian. Unlike them, she does not appear to have "the communicative rights to use teacher-pupil interactions as a tool for constructing and acquiring knowledge" (Black, 2004b, p. 17). A demonstration of these rights is evident in Chris' behaviour in the next extract, where the pupils are engaged in a subtraction task, but Chris has made an error: