What is the key to retaining learned study materials? We examine the role that direct queries play in the retention of category information acquired through inference learning. In inference learning, learners predict an unknown property of an item given its other properties and category membership. We manipulated query frequency across properties during inference learning and found that properties that were queried less often were remembered as well as properties that were queried more frequently. These effects extended from minutes to multiple day delays. Thus, asking about properties during inference training only a few times can immediately promote learning and greatly enhance the long-term retention of category knowledge. We situate our results in the broader memory and education literatures and consider how these findings constrain the development of category learning models.