This study examines object construction and the ages at which children developing under various environmental conditions achieve five of the landmarks in the Uzgiris-Hunt (1974) scale of object permanence. (Author)

A series of Piagetian concrete operations period tasks dealing with classificatory concepts was administered to 280 children (40 subjects from each of seven levels--preschool, kindergarten, and first, second, third, fourth, and sixth grades). Significant main effects for age were found for all the tasks. Few significant sex differences were…