Increasing concern over the mathematics programs in our public schools within the last decade has led to attempts to upgrade the mastery of mathematics. Although such curricular attempts arc presented as an indivisible whole, it has been suggested they are tied together by a few basic strands or fundamental concepts that run through the curriculum. This theme is pursued in the Twenty-fourth Yearbook of the National Council of Teachers of Mathematics.1 In California, these themes or basic strands have been classified as number and operations, geometry, measurement, and applications of mathematics.2 Other strands labeled sets, funct ions and graphing, logic, and the mathematical sentence are seen as topics cutting across various systems. Taking direction from these reports, this study investigates the mastery and undcrstandi ng of one of these strands—measurement—among students enrolled in “modern school mathematics.”