In this experiment, the authors sought to further examine the effects of pretests on later learning. Specifically, they were interested in if activating a correct mental representation on the pretest would improve later learning and if activating an incorrect representation would impair learning. Kindergarteners and preschoolers were split into three groups: one group took a pretest designed to activate a detrimental logarithmic representation, one took a pretest designed to activate a beneficial linear representation, and a control group received no pretest. After a short feedback session, all children completed a posttest to determine if they had learned from the feedback. (Contains 2 figures and 2 footnotes.)