3D shapes all around us
๐ In short
A dice, a tin can, a football and an ice cream cone are all 3D shapes. A 3D shape has length, width and height: we can hold it and look at it from every side. It has faces, edges and vertices.
๐คฉ Did you know?
- The Great Pyramid of Giza was built about 4500 years ago from millions of stones.
- Cubes, pyramids and prisms follow Euler's rule: faces + vertices โ edges = 2.
- A sphere rolls in every direction, a cylinder rolls in one direction, and a cube doesn't roll.
- Milk cartons are cuboids because they stack in the fridge with no gaps.
๐ Find out more
๐ Faces, edges and vertices
A face is a surface of the shape, like a cube's square face. An edge is a line where two faces meet. And a vertex is a point where several edges meet. A cube has 6 faces, 12 edges and 8 vertices.
๐ Cubes and cuboids
A cube's six faces are equal squares, like a dice. A cuboid's faces are rectangles, like a milk carton, a shoebox or a book.
๐ก Round 3D shapes
A cylinder has two round bases and a curved surface, like a tin can. A cone has a round base and a point, like an ice cream cone. And a sphere is one curved surface with no edges or vertices.
๐ฏ Pyramids and prisms
A pyramid has a base and triangular faces that meet at one point, like the pyramids of Egypt. A prism has two matching bases, like a tent whose two ends are triangles.
๐ See it in a picture
๐งฎ Worked examples
- Cube: 6 + 8 โ 12 = 2Faces + vertices โ edges.
- Pyramid: 5 + 5 โ 8 = 2Euler's rule works for the pyramid too.
๐ Key words
- 3D shape
- A shape with length, width and height
- Face
- One of the surfaces around a 3D shape
- Edge
- The line where two faces meet
๐งช Try it at home
Make a cube from card: draw 6 equal squares in a cross shape, cut it out, fold it and glue it. Then count its faces, edges and vertices with your finger.
๐งฉ Test yourself
1 How many faces does a cube have?
2 Which 3D shape looks like a tin can?
3 Which 3D shape has no edges or vertices?