Exploring prospective primary school teachers? perceptions of pupils? mathematical thinking in a pro- portionality problem.

In order to ensure an optimal teaching and learning process, the mathematics teacher must be able to analyse, interpret and as-sess the mathematical activity of his/her students when they solve the tasks he/she sets them. This competence enables the teacher to understand the learning achievements and difficulties that students show to make relevant decisions for action. The aim of this paper is to describe and analyse the competence of a group of 130 prospective primary school teachers to interpret students' responses to a situation of proportionality (comparison problem). Among the results obtained, we highlight an insufficient didactic-mathematical knowledge of proportional reasoning, which prevents future teachers from interpreting in a relevant way the degree of correctness in the solutions or the apparent mathematical thinking of the students.