Attributes of Three-Dimensional Shapes

Three-dimensional (3D) shapes are solid figures that take up space. Unlike flat 2D shapes, you can hold 3D shapes in your hand! To understand 3D shapes better, we look at their special parts, called attributes.

The Three Main Attributes

Every 3D shape with flat sides has three main parts you can count:

1. Faces: A face is a flat surface on a 3D shape. If you look closely at a face, you will see it is actually a 2D shape, like a square or a rectangle!
2. Edges: An edge is the straight line where two faces meet.
3. Vertices (Corners): A vertex (plural: vertices) is the pointy corner where three or more edges meet.

Common 3D Shapes and Their Attributes

Let's look at some common solid shapes and count their faces, edges, and vertices.

Cube

A cube looks like a standard building block or a dice.

• Faces: $6$ faces. Every single face is a flat square.
• Edges: $12$ edges.
• Vertices: $8$ vertices.

Rectangular Prism

A rectangular prism looks like a cereal box or a brick.

• Faces: $6$ faces. Most or all of these faces are rectangles.
• Edges: $12$ edges.
• Vertices: $8$ vertices.

Triangular Prism

A triangular prism looks like a camping tent.

• Faces: $5$ faces. It has $2$ triangle faces on the ends and $3$ rectangle faces on the sides.
• Edges: $9$ edges.
• Vertices: $6$ vertices.

Practice Questions

Here are some questions to test your knowledge of 3D attributes:

• How many edges does a rectangular prism have? Count the straight lines: a rectangular prism has $12$ edges.

• What shape are the faces of a cube? If you look at any flat side of a cube, it is a perfect square.

• How many vertices does a triangular prism have? Count the pointy corners: a triangular prism has $3$ corners on one triangle end and $3$ on the other, making $6$ vertices in total.