COMMON NOMINATOR OR COMMON DENOMINATOR? TEACHERS' VIEWS ON COMPARING FRACTIONS

Tasks play a crucial role in mathematics teaching. In this paper we present a task that was developed for elementary school teachers in a professional development program. The formulation of the task was based on an observation of Dana, a participant in the program, who visited Betty in class. The formulation of the task in the specific manner presented in this paper set the stage for a communicative analysis of mathematical and didactical occurrences.