This study reports on teacher-interns' observations of research sessions involving urban students participating as subjects in an informal mathematical learning afterschool program. The research comes from a project that investigates how minority students from low-income, urban community build mathematical ideas and engage in mathematical reasoning. Videotape data from debriefing sessions of the research team, including teacher interns, show that teacher-interns attend to the behavioural and cognitive aspects of the students' mathematical activity as well as the research interventions. [For complete proceedings, see ED496859.]