A concept map is a two-dimensional, graphic or schematic diagram illustrating the interconnections, and often the hierarchy, of a particular concept or topic. Concept maps are especially important in teaching science because they depict the interrelationships among the members of a group or a system. Concept maps are often used in science to represent ecosystems, mechanical systems, and social systems. This Toolkit column provides meaningful ways to make the most of concept maps, especially in the area of assessment.