Running head: GEOMETRY, WORKING MEMORY AND INTELLIGENCE

Although geometry is one of the main areas of mathematical learning, the cognitive processes underlying geometry-related academic achievement have not been studied in detail. This study explored the relationship between working memory (WM), intelligence (g-factor) and geometry in 176 typically-developing children attending school in their 4 th and 5 th grades. Structural equation modeling showed that about 40% of the variance in academic achievement and in intuitive geometry (which is assumed to be independent of a person’s cultural background) were explained by WM and the g-factor. After taking intelligence and WM into account, intuitive geometry was no longer significantly related to academic achievement in geometry. We also found intuitive geometry closely related to fluid intelligence (as measured by Raven) and reasoning ability, while academic achievement in geometry depended largely on WM. These results were confirmed by a series of regressions in which we estimated the contributions of WM, intelligence and intuitive geometry to the unique and shared variance explaining academic achievement in geometry. Theoretical and educational implications of the relationship between WM, intelligence and academic achievement in geometry are discussed.