Since the measurement of school achievement involves the administration of achievement tests to various grades on various subjects, both grade level and subject matter contribute to within-school achievement variations. To determine whether achievement test scores vary most among different fields within a grade level, or within fields among…

This study investigated: (1) whether boys and girls master formal reasoning tasks to the same degree at the same age; (2) if the variance of boys' and girls' performance in formal tasks could be predicted by the same cognitive learning abilities; and (3) what are the main and interactional effects of age, sex, and school type on the variance of…