The purpose of the study was to examine the effect of instruction using Dienes' perceptual variability principle on the development of ability to operate with symbols in a meaningful way. The following was studied: whether an increase in the number of enactive and/or iconic embodiments of a concept utilized in an instructional episode will produce a corresponding increase in the proportion of students that reach criterion on a transfer test involving the symbolic embodiment of the concept. Three instructional treatments in programmed format were devised for three sets of four objectives on the concept of equivalent fractions: T1, using an array of blue and red disks; T2, using the disks and an array of shaded and unshaded circles; and T3, using the disks, the circles, and partially-shaded rectangles. Eighty-one students were selected and randomly assigned to the three treatments on all three sets of objectives (if pretest evidence indicated that had not achieved them) or on only one set of four objectives (which they had not achieved). The proportion of T1 students reaching criterion on the transfer test was not less than the proportion of T2 students reaching criterion on the test; T2 was not less than T3. It was concluded that instruction using one, two, or three enactive and/or iconic embodiments of a concept had essentially the same effect on the ability of average to above-average students to operate with a symbolic embodiment of the concept. (Author/MS)