Providing exploratory activities prior to instruction has been shown to facilitate learning. However, questions remain regarding the provision of guidance during the exploration phase. In this study, we replicated and extended a previous experiment by examining the effects of feedback during exploratory problem solving for children with varying levels of prior knowledge. Ninety-five children (M age ≅ 8 yrs) solved 12 novel math problems and then received brief conceptual instruction. After solving each problem, they received (a) no-feedback, (b) outcome-feedback, or (c) strategy-feedback. Consistent with the previous experiment, the results resembled an aptitude by treatment interaction. Feedback during exploration prior to instruction improved children’s procedural knowledge, but only for those with low prior knowledge. For children with higher prior knowledge, no feedback resulted in better procedural knowledge. Results suggest that providing feedback may not always be optimal.