A polyhedron is a closed, three-dimensional solid bounded entirely by at least four polygons, no two of which are in the same plane. Polygons are flat, two-dimensional figures (planes) bounded by straight sides. A square and a triangle are two examples...

A polyhedron is a three-dimensional closed surface or solid, bounded by plane figures called polygons. The word polyhedron comes from the Greek prefix poly-, which means "many," and the root word hedron which refers to "surface." A polyhedron is a...

A polyhedron (plural polyhedra or polyhedrons) is often defined as a geometric object with flat faces and straight edges (the word polyhedron comes from the Classical Greek πολυεδρον, from poly-, stem of πολυς, "many," + -edron, form of...

What kind of spatial understanding do first and second graders have? What do they see when they look at three-dimensional objects? What words do they use to describe what they see? How might their visualization skills be sharpened by building and describing three-dimensional...

Mathematician William T. Webber has discovered how to construct a toroidal polyhedron from a flat rectangular piece of paper, cardboard or plastic. Webber, who specializes in topology, has used a computer program to prove that the figure is a true toroidal polyhedron. Why...