The goal of the present study was to examine the mechanisms underlying a strategy that we developed to make instructional explanations effective. In two experiments participants learned about plate tectonics from a multimedia material, including adjunct explanations that revised common misunderstandings. These explanations were either marked (including a device that pointed out the misunderstanding that the explanation was intended to revise) or unmarked. In both experiments participants receiving marked revising explanations outperformed those receiving unmarked ones in retention and transfer. In Experiment 1, think-aloud protocols revealed that marked revising explanations enabled learners to detect and repair flaws in their understanding more frequently than unmarked explanations. In Experiment 2, time recordings revealed that participants in the marked condition spent more time processing the revising explanations. Overall, the results mean that the revising instructional explanations that point out learners' misunderstandings promote a revision-oriented processing, in which learners monitor and revise their own understanding. (Contains 2 figures and 4 tables.)