This experiment investigated the effect of the presentation of a globe--the culturally accepted artifact representing the earth--on children's reasoning in elementary astronomy. Forty-four children from grades 1 and 3 were interviewed individually. First, the children were asked to make their own representations of the earth (i.e., drawings and play-dough models) and to indicate where people live on the earth. Then, the same children were presented with the globe and were asked to answer another set of questions regarding the shape of the earth and the areas where people live. The results showed an increase in the frequency of correct responses with the presentation of the globe, but also a decrease in the overall consistency of responses. Only some (the older) children could profit from the presence of the artifact to construct an internally consistent scientific model of the earth. Many children employed a mixed way of responding, sometimes basing their answers on the externally provided model and sometimes on their prior knowledge. These latter children did not seem to be aware of what they were doing. It appears that in the absence of an external, cultural model, children can form internal representations which they can distort in ways that make them consistent with their prior knowledge. But, when the cultural artifact is present, such distortions are not possible with the result that children end up with internally inconsistent patterns of responses.