Into the Third Dimension: Exploring 3D Shapes

Pick up any object near you — a box, a tin, a ball, or a book. Look at it closely. How many flat or curved surfaces can you count? How many corners? You are already exploring 3D shapes without even knowing it! A 3D shape is any solid object that takes up real space — you can hold it, stack it, or roll it.

Every 3D shape is described using three key properties: faces, edges, and vertices. A face is a flat or curved surface on a 3D shape. The flat top of a tin can is a face. An edge is a straight line where two faces meet. Think of the corner of a cereal box — run your finger along it and you are tracing an edge. A vertex (say: VER-tex) is a pointy corner where edges meet. The word for more than one vertex is vertices (say: VER-ti-seez). Now let's meet five common 3D shapes: • Cube — 6 square faces, 12 edges, 8 vertices. A dice is a cube. • Cuboid — 6 rectangular faces, 12 edges, 8 vertices. A cereal box is a cuboid. • Sphere — 1 curved face, 0 edges, 0 vertices. A football is a sphere. • Cylinder — 2 circular flat faces and 1 curved face, 2 edges, 0 vertices. A tin can is a cylinder. • Cone — 1 circular flat face and 1 curved face, 1 edge, 1 vertex (the pointed tip). A party hat is a cone. Notice that curved surfaces still count as faces — but they are curved faces, not flat ones.