Compares various methods of defining derived quantities, arguing for a definitional formula using base or fundamental units in a word equation, or symbol-equations with the symbols explained. Suggests that fundamental units be defined operationally or left regarded as intuitive as in the case of length and time. (JM)

Considers several aspects of quantitative relationships involved in learning physics. Includes discussions of proportionality, various kinds of equality, and the need for generality. Argues that clear distinctions are necessary if the physics curriculum is to be examined with regard to pupil outcomes. (TW)