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…

This research attempts to diagnose the skills required for successful spatial performance in order to provide a theoretical foundation for military training in such tasks as map reading, surveying, and navigation. It is known that successful performance on spatial tasks depends on task requirements (e.g., requisite knowledge, alternative paths to…