Very long-term retention of the control of variables strategy following a brief intervention

Middle school students (n = 354) were tested for their understanding of the control of variables strategy (CVS) 2.5 years after participating in a study comparing three different interventions for teaching CVS. The key finding was that the pattern of effects observed in the 4th grade continued to be observed in the 6th grade. This was because (a) students who had mastered CVS in the 4th grade were likely to continue to perform at mastery levels in the 6th grade whereas (b) the learning of students who had not mastered CVS in 4th grade was independent of the teaching intervention they had received in the 4th-grade study. These findings demonstrate that a brief intervention of direct instruction in CVS can produce long-lasting learning of the principle of controlling variables.