Three-Dimensional Shapes

While 2D shapes like squares and circles are flat, three-dimensional (3D) shapes are solid. You can hold them in your hand! Everything around us in the real world is made of 3D shapes, from your favorite toys to the food you eat.

Parts of a 3D Shape

To describe 3D shapes, we look at three special parts:

• Faces: The flat surfaces on the outside of the shape.
• Edges: The straight lines where two flat faces meet.
• Vertices (Corners): The pointy spots where edges meet.

Common 3D Shapes You Should Know

1. Sphere

A sphere is perfectly round, just like a bouncy ball or a globe.

• Faces: $0$
• Edges: $0$
• Vertices: $0$
• Fun fact: Because it has no flat faces or edges, a sphere can roll in any direction!

2. Cube

A cube looks like a building block or a pair of dice. Every flat surface is a perfect square.

• Faces: $6$ flat square faces
• Edges: $12$
• Vertices: $8$

3. Rectangular Prism

This shape looks like a stretched-out cube. Think of a cereal box or a thick book.

• Faces: $6$ flat rectangular faces
• Edges: $12$
• Vertices: $8$

4. Cylinder

A cylinder is round on the sides but has flat circles on the top and bottom. A soup can or a battery is a cylinder.

• Faces: $2$ flat circular faces
• Edges: $0$ (it has round borders, but no straight edges)
• Vertices: $0$

5. Cone

A cone has a circle on the bottom and points to a tip at the top. Think of a party hat or an ice cream cone!

• Faces: $1$ flat circular face
• Edges: $0$
• Vertices: $1$ (the pointy tip at the top)

How Do They Move?

Because of their different parts, 3D shapes move in different ways:

• Roll: Shapes with curved parts can roll. (Spheres, cylinders, and cones).
• Slide: Shapes with flat faces can slide across a table. (Cubes, rectangular prisms, cylinders, and cones).
• Stack: Shapes with flat faces on top and bottom can be stacked. (Cubes, rectangular prisms, and cylinders).

Example Problems

1. How many faces does a cube have? Think of a dice. It has numbers $1$ through $6$ on it because a cube has exactly $6$ flat faces.

2. Which 3D shape can roll and slide? A cylinder can roll on its round side and slide on its flat circular faces. A cone can also roll and slide!

3. Name the shape of a can. A can has two flat circular faces and a round body. It is a cylinder.