Three-dimensional (3D) shapes have width, height, and depth. 2D shapes only have width and height.
2D shapes are flat, just like stick figures.
3D shapes are solid shapes that take up space. Your body is 3D.
Let's review the most common 3D shapes, starting with pyramids.
The pyramids of Egypt are huge examples of rectangular pyramids.
A pyramid has a flat base and triangle-shaped faces.
The shape of the base and total number of faces are different for different types of pyramids.
The example above is a rectangular pyramid. It has a rectangular base and four faces.
Below is a triangular pyramid.
It has a triangular base and three faces.
This is the Leaning Tower of Pisa.
It's shaped like a cylinder.
A cylinder has two flat circular bases.
These two bases are joined by a curved surface.
What do these objects have in common?
Yes.
They're all shaped like a sphere,
A sphere has no edges, no faces, and no corners. It has only one perfectly curved surface.
When we think of examples of spheres, we think of our planet Earth.
Marbles are spheres too.
Ice cream often comes in cones.
A cone has a flat base. This base is joined to a point by a curved side.
The point at the tip is called the vertex.
The hats that we wear at birthdays are shaped like cones.
This toy is a Rubix cube.
A cube is a 3D shape that has 6 square faces (or sides). These faces are all the same size.
This box is shaped like a cube.
Can you think of other things that are shaped like a cube?
Prisms are 3D shapes with identical ends that face each other, and flat sides. Prisms have no curves at all.
Cubes are a type of prism.
Let's look at two other types of prisms.
The roofs of many houses are shaped like triangular prisms.
A triangular prism has two triangle bases that are joined together by rectangular sides.
The two triangle bases are facing each other.
This is a rectangular prism.
It's really similar to a cube, just a bit longer.
A rectangular prism is made up of 6 rectangles. Opposite sides are the same. One of the pair of sides are the bases. The other four rectangles connect the two bases.
Many houses, buildings, and rooms are made up of rectangular prisms.
The body of the house is a cube. It has 6 square sides. Some houses are shaped like rectangular prisms.
The roof of the house is a triangular prism. It has 2 triangles connected together.
Great job.
Now, you're ready to ace the practice.