Faces of 3D Shapes
In this video, we will learn how to name the 2D shapes that are the faces of 3D shapes. Can you name all of these 3D shapes? This is a cube. This is a cylinder. We call this shape a cuboid. Another name for this shape is a rectangular prism. This is a cone, and this is a pyramid. Did you get them all right?
When we’re describing 3D shapes, we sometimes think about the number of edges they have. This is an edge. And we call the points where two edges meet a vertex. If we’re talking about more than one vertex, we use the plural, which is vertices. We call the flat surfaces of 3D shapes faces. A cube is made from square faces.
A good way to learn about 3D shapes is to try making some of your own. How would we make this cube? To make a cube of your own, you will need six squares. Cubes have six square faces. Which 3D shape is the girl about to make? Here’s a clue. The faces are all triangles. Which 3D shape could we make from these four triangular faces? It’s a pyramid.
This is a cuboid or a rectangular prism. If we wanted to make a box like this, which 2D shapes would we have to draw? The faces of this cuboid are all rectangles or squares. This is what the box or the cuboid would look like if it was flat. Which 3D shape could we make using a square and these four triangles? It’s a pyramid.
Some 3D shapes have curved surfaces as well as flat faces. If we wanted to make a cylinder, we’d have to bend this piece of card into a tube to make the surface curved. And we’d also need two circles. Let’s try some questions now so we can practice naming the 2D shapes which make the faces of 3D shapes.
What shape are the faces of the cube? Are the faces triangles, rectangles, squares, or circles?
If we were to join these four vertices, one, two, three, four, which 2D shape have we made? It’s a square. The faces of the cube are square.
What shape is the shaded face on the pyramid? Is it a circle, a triangle, a trapezoid or trapezium, or a rectangle?
We’re shown a model of a pyramid. The pyramid has one of its faces shaded. We have to choose the shape of the shaded face. If we join together these vertices, we can see which 2D shape the face is. It’s a triangle. The shaded face on the pyramid is a triangle.
How many faces does this shape have? How many of its faces look like this rectangle? How many faces are squares? And how many faces are circles?
We’re shown a model of a 3D shape. Do you know the name of this shape? It’s a cuboid or a rectangular prism. We can imagine that this cuboid is a cardboard box. And if we were to flatten the box, it would look like this. Thinking of the 3D shape in this way helps us to count its faces. How many of the faces are rectangles? There’s one, two, three, four rectangular faces.
How many of the faces are squares? There are two. How many of the faces are circles? The shape doesn’t have any circular faces. If four of its faces are rectangles and two are squares, the cuboid has six faces. Four plus two is six. The cuboid has six faces; four are rectangles, two are squares, and none are circles.
Pick the shape that matches the description. It has two faces that are triangles. And it has three faces that are rectangles.
We’re shown four different 3D shapes. We have to find the shape that has two faces that are triangles and three faces that are rectangles. This is a cuboid. It does have some rectangular faces, but none of its faces are triangles. We know this isn’t the shape that matches the description.
This shape is a pyramid. It does have triangular faces, but none of its faces are rectangles. This shape is also a pyramid, but one of its faces is a square. It doesn’t have any rectangular faces, so this is not the shape that matches the description either.
This must be the shape that matches the description. It does have two faces that are triangles. Does it have three faces that are rectangles? There’s one rectangular face at the bottom, another one at this side, and here’s another rectangular face. This shape does have three faces that are rectangles. This is the shape that matches the description. It has two faces that are triangles and three faces that are rectangles.
What have we learned in this video? We’ve learned how to name the 2D shapes that are the faces of 3D shapes.