Two studies investigated the functional equivalence of three different scoring systems used to assess the child's ability to understand and carry out multiplicative classification tasks. All three scoring criteria produced reliable and homogeneous tests. Their factor matrices were similar, and the corresponding factor structures were invariant…

Piaget's model of children's conceptual learning and development was compared with Klausmeier's Conceptual Learning and Development (CLD) model in a longitudinal study. The CLD model suggests four successive levels of concept learning: (1) concrete--recognizing an object which has been encountered previously; (2) identity--recognizing a known…