The study of 3-dimensional shapes is a part of geometry. All 3-dimensional figures must have height, width and length. Their flat surfaces are called faces, the sides of which are called lateral faces. Edges are formed where faces meet, and vertices are formed where edges meet.

Examine the shape to determine if it meets the criteria for a 3-dimensional shape: height, width and length. A picture of a 3-dimensional shape is 2-dimensional. The actual object we can touch is 3-dimensional.

Identify 3-dimensional shapes with curved surfaces. A sphere is a symmetrical, 3-dimensional figure shaped like a ball. It has no flat sides and no corners. Every point on the curved surface of the sphere is equidistant from the center of the sphere. A cone has a flat base that is circular in shape, topped with a rotated, right-angled triangle that results in a curved surface ending in a point, called a vertex.

## Sciencing Video Vault

Locate shapes with all flat surfaces (or faces). How many are there? A triangular prism is a 3-dimensional shape with three rectangular sides, and two ends that are triangles. A triangular prism has a triangular cross-section all the way along its length. Rectangular prisms have six faces that are all rectangles, with a cross-section that is a square. Cubes are equal in height, width and length. All six faces are square. Rectangular prisms and cubes, which are also prisms, are called cuboids.

Look for examples of 3-dimensional shapes in everyday life. Basketballs are spheres. Ice cream cones are cones. A pup tent is a triangular prism. A gift box is a rectangular prism. Dice are cubes.

Make paper examples of various 3-dimensional shapes. Adding a “hands-on” element to learning these shapes increases familiarity.