Strategies young children used to correct errors in nesting seriated cups changed substantially with age, becoming increasingly more flexible and involving more extensive restructuring of the relationships among the cups. The same trend toward increasing flexibility of thought and action also appeared in procedures children used to combine the…

Describes longitudinal study of the development of understanding of two logical properties of number by 36 children during the first three years of primary school in Glasgow. Piagetian tests and number skills tests were administered to explore the acquisition of number as class and number as order concepts. (Author/LRW)