Objective.

This work mainly aims to compare the assessment criteria considered most relevant by Mathematics teachers in Elementary Education with those they actually use and the perception their students have.

Method.

To this effect, we interviewed 30 teachers and 120 students. Additionally, the teachers participated in a blinded assessment of one student’s exam based on the criteria discovery method. They were asked to grade a test involving several mathematical tasks which a student had previously solved. They could ask questions to the interviewer without seeing the document.

Results.

Based on the transcriptions of the interviews, a content analysis was conducted to categorize and compare the assessment criteria expressed (by the teachers), perceived (by the students), and those used (in the blind assessment).

Discussion and conclusions.

The results suggest that teachers consider mental arithmetic, comprehension, and, above all, mathematical reasoning as the most important criteria. However, most of their students do not have the same perception. Furthermore, a third of the teachers are not sufficiently aware of the assessment criteria they are, in fact, using. Finally, we discuss the influence of assessment in mathematics.