Evaluation can be seen as a teaching strategy which allows us to identify the theories and hypotheses that students form for themselves as very young children, the constructive errors they commit when resolving problems and, in general, their previously acquired knowledge. All this facilitates the pedaeogieal activity of the teacher, in so lar as it makes it possible to adjust teaching strategies to the learning potential of the students and to the complexity of the object of knowledge. If we accept that students construct and reconstruct their knowledge in a learning process, we might agree that learning means giving new meaning to skills. Learning realities cannot be except in terms of the learning potential of each student, as given by his cognitive make up, his knowledge (curricular and extra—curricular), his values, his system of belief, etc. leaching always entails evaluating the skills of the student, proposing the correct strategies for the student to progressively restructure and give new