Twenty-two children (ages 5-8) with mild mental retardation who received learning set instruction on unidimensional classification and seriation improved on these precursors to concrete operations; 22 children who received more conventional instruction did not. Improvement on classification and seriation was accompanied by improvement on measures…

This study with 22 adults with mild to moderate mental retardation examined the nature of knowledge structures in this population as well as effects of presentation methods and response methods on ability to classify items. Results indicated major effects for disability severity, insignificant findings for presentation method, and a trend toward…