Role of measurement operations in the acquisition of conservation

Provided 17 kindergartners (nonconservers) with experiences which focused upon the conservation of continuous quantities in terms of the numeration and comparison of discrete units of liquid quantity. The effects of training facilitated the conservation of continuous quantity and transferred to the conservation of area, mass, quantity, number, and length. The explanations offered for conservation by the trained conservers were analogous to those elicited from a group of 17 "natural" conservers, and the effects of training were maintained over a 7-mo period. Results are interpreted in terms of the development of a quantitative set which supplants the existing perceptual set. Certain measurement operations were hypothesized to be the effective source of this perceptual-quantitative shift.