This paper reports the organization of a group of four teachers who planned, developed, and evaluated a teaching proposal. The aim of this study was to discuss the education of teachers who teach mathematics for the Elementary School, considering the challenge of organizing a Guiding Activity for Geometry Teaching. In order to do so, the researchers referred to the Historical-cultural Theory, more specifically to the Activity Theory (Leontiev, 1983; 1988) and the Educational Guiding Activity (Moura, 1996; 2010). It was possible to show that the teachers' mathematical knowledge served as guidance for the teaching practices, and that their sharing proved to be preponderant for their constitution as teachers.
Teachers' Education; Elementary School Education; Mathematics Education; Geometry Teaching