Examines strategies used by first grade children in performing a seriation task, using materials varying in length or weight. Most first-grade children employed a concept-task-strategy in serially ordering objects by length and weight. In addition Piaget's observation that length can be serially ordered before weight was upheld. (CP)

Research was done to investigate the interfunctional relationships between a child's ability to order a set of objects and the development of language descriptives used to describe differing aspects of a group of objects which had been ordered. Results show that mean age of concrete operation acquisition is 7.1 years. (Author/JB)

Demonstrated is a covariance principle that causes the observer to assume that if one aspect of a two-dimensional figure (its perimeter or its area) is conserved, the other aspect must also be conserved (pseudo-conservation). Mentally retarded individuals, assuming no such fixed relationship, correctly judged the changed state of the nonconserved…

This study examined the effect of an innovative teaching activity to improve concrete operational thinking skills with preschoolers in Head Start programs. A "learning set" of classification games and seriation games was used to teach the oddity principle and insertion into a series. These games were played with the children using toy ponies and…