Prisms All Around Us
Many everyday objects are prisms: a cereal box is a rectangular prism, some chocolate boxes are triangular prisms, and many pencils are hexagonal prisms before they are sharpened. Folding the paper versions helps children recognize these shapes and name their faces.
How an Antiprism Differs
Turn one base of a prism by half a side and the squares between the bases no longer fit: in their place comes a band of triangles, pointing up and down in turn. That zigzag band is what makes an antiprism. With two triangles as bases, the antiprism is the octahedron.
Counting Faces, Edges and Corners
A prism whose base has n sides has n + 2 faces, 3n edges and 2n corners; an antiprism has 2n + 2 faces, 4n edges and 2n corners. Checking these numbers on the folded models is good practice in geometry and in careful counting.