Testing has been proven to be a powerful tool to enhance meaningful learning, but little research has directly examined retrieval-based learning in children. Two experiments investigated through a transfer test whether retrieval practice can facilitate the acquisition of high-level cognitive skills, focusing on the control-of-variables strategy. In two experiments, children of grade 5 and 6 (n = 165/217) initially received a lesson based on a textbook chapter on the control-of-variables strategy. In Experiment 1, we compared the effects of retrieval practice (free recall) and restudy. In Experiment 2, we compared effects of retrieval practice (cued recall), restudy and practically performing an experiment. The results indicate an important limit of retrieval practice in children, as in both studies restudy outperformed the other learning activities. Participants’ metacognitive predictions are in contrast to the actual findings, as they predicted performing an experiment as the most effective learning activity.