Two-dimensional (2D) shapes are completely flat. They cannot be picked up. A polygon is a 2D shape with straight sides that meet at vertices. Polygons have names that show the number of sides they ...

Named for Plato, who theorized that the classical elements were made of these regular polyhedrons, three of the Platonic solids are composed of equilateral triangles: the tetrahedron, octahedron, and ...

The net of a 3D shape is what it looks like if it is opened out flat. There are many types of nets for the different 3D shapes. A net is made from polygons that can be folded and joined to make a ...