Little is actually known about the assessment practices of elementary school teachers in mathematics in France, while institutional recommendations regarding evaluation were recently introduced. We adopted a didactic approach to study the assessment practices of elementary school teachers in mathematics, by considering more specifically the nature and the complexity of the tasks proposed during tests given in classroom. We applied a didactic tool declined in factors of complexity and skill to analyse assessment tasks. We were thus able to realise that the tasks given in classroom assessment by the 25 teachers in our sample were mostly of a low level of complexity and competencies, and that they corresponded almost exclusively to tasks with which the pupils had been confronted during the sessions having preceded the evaluation. This study also revealed elements related to teachers’ assessment skills.