Video Transcript
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.
