In two experiments we investigated the hypotheses that a) the refutation of more than one alternative conception, and b) the inclusion of categorical information in a refutation text will facilitate elementary school children's understanding of the scientific concept of the Earth. The results of the first experiment showed no clear support of the first hypothesis but suggested that the inclusion of categorical information-information about the ontological category in which a concept belongs-is more effective than other kinds of information. The second experiment controlled for the amount of information and compared only the inclusion of categorical vs. non-categorical information in refutation and non-refutation texts. The results showed that the texts that included the categorical information improved children's understanding of the scientific information more than all the other texts. This result needs to be replicated using more examples from other science domains.