Augmented Reality has been used for developing systems with learning purposes. In this paper, we present an Augmented Reality system for learning the interior of the human body. We have tested the system with children of the Summer School of the Technical University of Valencia. In this test we have analysed if the use of a Head-Mounted Display or a typical monitor influence in the experience of the children. Results do not offer statistical significant differences using both visualization systems and confirm that children enjoyed learning with the system and consider it as useful tool not only for learning the interior of the human body but also for learning other subjects.