Polyhedron facts for kids

A polyhedron (one polyhedron, many polyhedra, or polyhedrons) is a geometrical shape. It has flat faces, and straight edges. Usually it is defined by the number of faces, or edges.
Mathematicians do not agree on what makes a polyhedron.
Naming
Usually, polyhedra are named by the number of faces they have. The first polyhedra are the tetrahedron, which is made of four triangles, pentahedron (five faces, can look like a foursided pyramid), hexahedron (six faces, a cube if it is regular), and heptahedron (seven faces, can look like a prism based on a pentagon, or a pyramid based on a hexagon amongst others).
Images for kids

A skeletal polyhedron (specifically, a rhombicuboctahedron) drawn by Leonardo da Vinci to illustrate a book by Luca Pacioli

The tetrahemihexahedron, a nonorientable selfintersecting polyhedron with four triangular faces (red) and three square faces (yellow). As with a Möbius strip or Klein bottle, a continuous path along the surface of this polyhedron can reach the point on the opposite side of the surface from its starting point, making it impossible to separate the surface into an inside and an outside.
See also
In Spanish: Poliedro para niños