The purpose of this study was to test the relative efficacy of two modes of instruction for promoting learning and retention of selected geometrical concepts. The subjects in this study consisted of 119 students from three seventh and two eighth grade mathematics classes in Pittsburgh, Pennsylvania. The students in each class were randomly assigned by ability, to either the individualized group or the traditional group. The experiment consisted of five 45‐minute periods per week for approximately six weeks. A 53‐item achievement test was administered to each group at the conclusion of the experiment. The retention test (55 items) was administered three weeks after the completion of the experiment. The results of the study did not indicate a significant effect on learning or retention due to the mode of instruction. There was however a slight trend favouring the individualized group.