A concept map (also known as a knowledge map) is a visual representation of knowledge of a domain. A concept map consists of nodes representing concepts, objects, events, or actions connected by directional links defining the semantic relationships between and among nodes. Graphically, a node is represented by a geometric object, such as a rectangle or oval, containing a textual name; relationship links between nodes appear as textually labeled lines with an arrowhead at one or both ends indicating the directionality of the represented relation. Together, nodes and links define propositions or assertions about a topic, domain, or thing. For example, an arrow labeled has beginning at a node labeled bird and ending at a wings node represents the proposition “A bird has wings” and might be a portion of a concept map concerning birds, as portrayed in Figure 1.