Abstract
This paper presents the results of an experiment which investigated elementary school children's conceptual knowledge about the earth. First-, 3rd-, and 5th- grade children were asked a series of questions about the shape of the earth. Children's responses to these questions revealed considerable apparent inconsistency. For example, many children said that the earth is round but also stated that it has an end or edge from which people could fall. A great deal of this apparent inconsistency could be explained by assuming that the children used, in a consistent fashion, a mental model of the earth other than the spherical earth model. Five alternative mental models of the earth were identified: the rectangular earth, the disc earth, the dual earth, the hollow sphere, and the flattened sphere. It is argued that these models are constrained by certain presuppositions which children form based on interpretations of their everyday experience. Some of these models (the rectangular earth and the disc earth) seem to be initial models children construct before they are exposed to the culturally accepted information that the earth is a sphere. In the process of knowledge acquisition, children appear to modify their initial models to make them more consistent with the culturally accepted model by gradually reinterpreting their presuppositions. Synthetic models (such as the hollow sphere and the flattened sphere) are generated by children as a solution to the problems arising from the inconsistency between their initial model of a flat earth and the culturally accepted, scientific model of a spherical earth. Children come to understand that the earth is a sphere only when the presuppositions that gave rise to their initial models have been reinterpreted.
