This contribution aims at reflecting on a revision of the idea of evaluation in compulsory schooling, starting from the perspective of Assessment as Learning, according to which the evaluation is itself a didactic action, a constant and progressive learning tool. It is described a part of the Research-Training path based on a question sharing between teachers and researchers. How, starting from the design of the task, can a teacher make the processes explicit to him/herself and to the students, which go through the task itself and that therefore become generative elements for the learning process? Those processes enable to understand which the dimensions of expertise that one wants to mobilise in the students are and which the meaningful operations that are observed and therefore evaluated along the action are. They become common threads linking design, action, evaluation and reflection and make the didactic intentionality of the teacher coherent with the awareness of the learner.