This research project investigates the role that teaching intervention plays in the destabilization of representations of the concept of formation of shadows of nursery school pupils. The resistance that this system of representations shows in the attempt to destabilize it has been studied with two groups of children, 5-6 years old. One of the groups (the experimental) participated in a teaching process which aimed to lead pupils to the construction of a precursor model ; the second (the control group) followed traditional teaching methods. In all experimental situations that were studied the progress between pre-test and posttest was significant for the subjects of the experimental group at the level of explanation of the phenomena of formation of shadows.