The aim of this research is to examine how children use visual variables to represent nominal and ordinal data on thematic maps. Greek students from first (six- to seven-year old), second (seven to eight-year-old), and third grades (eight- to nine-year-old), without any systematic cartographic experience, were invited to participate in the composition of thematic maps at the stage of symbolization of various lists of items/attributes, using a specially designed software tool. The results revealed that many students, when making cartographic decisions, discovered basic principles of the application of visual variables in symbolization of nominal and ordinal data and expressed their preferences. (Contains 6 figures and 6 tables.)