Using multitrait, multimethod data, and confirmatory factor analysis, the current study examined the effects of arithmetic item formatting and the possibility that across formats, abilities other than arithmetic may contribute to children's answers. Measurement hypotheses were guided by several leading theories of arithmetic cognition. With a…

Analysis showed that a word problem is difficult to solve if: it is of a different type from the problem that preceded it; its solution requires a large number of different operations; its surface structure is complex; it has a large number of words; or it requires a conversion of units. (Authors)