Researchers of mathematics education have been paying attention to the affective aspect of learning mathematics for more than one decade. Different theoretical frameworks have been suggested to analyze this aspect, where we utilize in the present research the discursive framework of Evans, Morgan and Tsatsaroni. This framework enables to link students' positions to their emotions. Here, we add to this relationship the metacognition variable, where we study how the added variable affects students' positioning in mathematical activities. A group of three Grade 7 high-achieving students participated in the research. They used GeoGebra to learn the topic of perpendicular lines through an authentic activity. The research results indicate that most of the means of claiming leadership were metacognitive in nature and were performed to enable the advancement of the group learning of the topic of perpendicular straight lines. These means were primarily requesting actions, initiating actions, performing actions, declaring actions, taking decisions, evaluation, monitoring and regulation. In one case, the claiming of leadership was accompanied with positive affect, namely enthusiasm, determination, and enjoyment. In the other case, the claiming of leadership was accompanied with different positive affect that included self-confidence and being proud of oneself.