"The importance of concept maps in expert learning has... been explained. Mappings of processes such as the design process are... related to the acquisition of procedural knowledge. ...[C]oncept maps may come in all shapes and sizes... Hyerle... distinguished between eight types of thinking map. A circle map helps define words or things in context and presents points of view. Bubble maps describe emotional, sensory and logical qualities. For example, at their center in a circle might be a heroic person, and from the center other circles describe the characteristics of the hero. Tree maps show relationships between main ideas and supporting details. Block schematic diagrams are examples of flow diagrams... Engineers often use such maps to show causes and effects as well as to predict outcomes. Maps may also be used to form analogies or metaphors and these are often used to try and explain s. ...Danserau and Newbern... called bubble maps 'node' maps. The nodes contain the central ideas. The links... show relationships between the nodes. ...They argued that concept maps should provide easy illustrations of complex relationships, less work clutter, be easy to remember, and easy to navigate. ...McAleese and Cowan warned that concept maps are only useful to the learner, if they are constructed by the learner. It is a view that is beginning to be taken up by the engineering community... [S]tudent constructed maps become the navigational tool that allows them to explore relevant content and expand their maps..."