Employing scientific reasoning when giving biological explanations comes easily to the experienced scientist. However, students often encounter difficulty when they attempt to explain biological phenomena. One significant obstacle appears to be the failure or inability to bear in mind the levels of organization. To address this issue, learning strategies, such as the yo-yo learning and teaching strategy, recommend moving across the levels of organization and making those levels explicit in the explanation. To support yo-yo learning, we developed a new graphic organizer, the zoom map. The zoom map combines the levels of organization with concept maps. It is specifically tailored to guide students in biology on ways to distinguish, interrelate and reflect the levels of organization. In this paper, we introduce the zoom map as a tool for instruction and diagnosis. We also provide evidence from teaching experiments that demonstrate how the zoom map benefited learning.