The purpose of the study was to determine whether kindergarten children could perform successfully on Piagetian class inclusion tasks and whether their performance was a function of the types of conditions under which the task was presented. Children were asked to classify items based on a physical attribute not visually perceptible (painted wooden beads and painted metal squares) or a physical attribute visually perceptible in the materials (candy suckers and paper circles). Classifications were also made according to the function of the items (things to eat, things to play with). Results generally supported Piaget's research. Children could classify on the basis of function more easily than when a physical attribute was used as the basis of classification. Results are discussed in terms of the children's use of numbers in solving these classification problems. (SBT)