Space Visualization Test on Pyramid Edges
When a pyramid is unfolded into a net, determining the way that the edges are connected requires some spatial thinking. The number in a triangle labels its thick edge. This Demonstration tests your space visualization by asking for the label of the thick edge marked by "?".
Each edge is is associated with two faces. The edges are numbered and displayed by triangulating the faces and putting the edge numberings into the adjoining triangles.