The diagram Marker and template

Over the past 25 years, visual representations have received considerable attention under the various designations of graphics, diagrams, visual aids, or simply pictures. No matter which name is used, the issue is whether their inclusion in instruction makes a significant difference in how and what students learn. The question of their importance extends naturally to schema theory. The most interesting issues have to do with how visual representations fit into the knowledge organization of a schema and what role they have in its access and use. 

It is reasonable to expect visual information to be a critical component of schema knowledge. As described in some detail in chapter 1, one of the earliest meanings of axn ia had to do with color, shape, and form. Certainly, the figural representation of a triangle entered into Aristotle s and Kant s conception of it and their elaboration of the triangle schema. 

Some research about visual representations in instruction has focused specifically on the use of diagrams, such as those in SPS. For example, Willis and Fuson (1988) found that children s performance on word problems improved when diagrams were used to display the problems, but they offered little psychological justification for the finding. 

For a likely explanation, we can turn to Larkin and Simon (1987), who viewed results like these in terms of computational efficiency. Larkin and Simon argue that verbal representations and diagrammatic representations may be informationally equivalent but computationally quite different. The use of diagrams to represent problems is preferable to verbal representation, they suggest, because diagrams facilitate the search process and enhance recognition. 

At the heart of this issue is the question of how diagrams are used by the learner. Potentially, any diagram has a dual nature. This duality was briefly discussed at the end of chapter 7. On the one hand, a diagram may function as a marker, serving as the 

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When the full-screen version of a diagram is used, only one diagram appears on the screen, and the task utilizes the template function of the diagram. When the miniature version is used by a task, all five diagrams appear together on the screen and the marker function is employed. 

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