THE SHELL IN THE STONE: WHAT CHILDREN SEE AND EXPLAIN

The described research activity aimed to investigate how mental models form and are used on topics of Earth sciences. A particular experiment was carried out in two classes of nursery school on a sample of 40 five-year-old children, as first step in a research that will subsequently involve also students of primary and secondary school. The research question of this first step was: “If the children are placed in front of a rock with fossil shells, found in the mountains, are they able to distinguish the shells (remains of living organisms) from the rock? If so: do they explain their presence in the rock, and how? Subsequently, the children are involved in an educational sequence on the formation of sedimentary rocks. Do the pupils use this experience to explain the presence of shells in the rock?” The children were interviewed one at a time before and after the learning sequence and both times they were asked to do a drawing of the rock in front of them. The results show that not all children have seen fossils in the rock. In the explanations of the children about the way in which the "rock with the shells" was formed, it seems to exist a hierarchy of complexity. It starts from no answers or seemingly meaningless answers to move on to explanations related to an anthropomorphic activity of the shells, up to invoke external causes capable of forming the rock (among the external causes we include human activity). Some children have indicated catastrophic natural events such as earthquakes or floods, which caused the formation of rocks containing shells. Someone has suggested the transport of the sea. Children's thoughts seem to retrace the path made by humanity to explain geological phenomena. The collected data indicate that, even for children of the same age, there are different degrees of complexity in the answers. The analysis of the answers and of the drawings shows that the learning activity influenced the children's thoughts. In this specific case, the disappearance of anthropomorphic ideas and the entry of catastrophic natural events could be evidence of an evolution of children's thinking, abandoning a naive idea to face a more complex thought. Some children seem to have discovered that the Earth and its rocks are not immutable, but they presuppose an internal or superficial movement.