Children's understanding of the commutative law of addition

This study analyzes the bases that support the comprehension ami development of the commutative law of addition. We presented two commutative tasks (compare sums and find the unknown addend) to 72 children from 5 to 8 years of age. Within each task we varied the presence/absence of the result, and the kind-of-addend. In general, our results show that children focus mainly on the addends in judging the equivalence between two commuted pairs. Equally, the errors and strategies analysis offers evidence of the children's inclination to focus on the addends, although older children also center on the results, especially in sorne conditions. Finally, we tentatively suggest a five level model of understanding of commutativity