Dodecahedron: Definition & Facts

Instructor: Chris Harrod

Chris has spent the past 16 years teaching all subjects in elementary school classrooms.

What do you call a shape with 12 sides that looks like a deflated soccer ball? A dodecahedron of course! In this lesson you will learn all about this special 3-D shape.

2-D and 3-D Shapes

Before we find out more about a dodecahedron, let's first learn about 2-D and 3-D shapes.

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Everywhere you look there are flat shapes. We call these flat shapes two-dimensional (2-D) since they only have two dimensions: length and width. Every 2-D shape has its own special name. For example, triangle is the name of a flat shape with 3 sides. A square has 4 sides.

A pentagon is the name of a 2-D shape with 5 sides. They almost look like a little house!

Regular Pentagon

But most shapes you see every day aren't 2-D. Instead they have three dimensions: length, width, AND depth. We call these kinds of shapes three-dimensional (3-D).

Three-dimensional shapes have parts called faces, edges, and vertices.

  • faces = the flat sides of the shape
  • edges = the lines where faces meet
  • vertices = the corners where edges meet

3-D shapes also have special names. For example, a cube is a 3-D shape that has 6 faces made of squares.

So What is a Dodecahedron?

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A dodecahedron is a 3-D shape that is made of 12 flat faces. There are many different types of dodecahedra, but the one we usually think of is made using 12 pentagons. When we put those pentagons together, we get a 3D shape that looks a little bit like a soccer ball. And no matter which way we look at it, it always looks the same.

You might be thinking that dodecahedron is a strange name. In fact, it really is the perfect name for this shape because dodeca- means '12' and -hedron means 'faces'. So dodecahedron actually means twelve faces!

Every dodecahedron has:

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