4. Shape Properties
When student develop a concept image (a mental image of a shape) without a concept definition
(a specified definition of the shape or its properties, they often identify examples of shapes, but
will also fail to identify examples of shapes that are not identical to their own mental image of
the shape or the shape prototype, i.e., the figure does not "look like" the shape. Although
characteristics such as orientation and proportions are irrelevant to the defining properties of a
shape, they affect whether students recognize certain shapes.