What is a Net? Fold 2D Shapes into 3D

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What this lesson covers

  • A net folds into a 3D shape.
  • Each face appears once in the net.
  • A cube has 11 different nets.
Key idea

What a net is

  • A net is a flat shape that folds up to make a 3D shape.
  • Every face of the 3D shape appears once in the net.
  • Faces joined along an edge in the net meet along that edge in the shape.
Worked example

Faces to look for

  • Count the faces first.
ShapeFaces
Cube6 squares
Cuboid6 rectangles
Triangular prism2 triangles and 3 rectangles
Square pyramid1 square and 4 triangles
Key idea

Nets of a cube

  • A cube has 11 different nets.
  • A cross shape works, but a row of four squares with two more on the same side does not.
  • Imagine folding: if two squares land on the same face, it is not a net.

Common mistakes

  • Any six joined squares make a cube.
    Some leave a gap, so test by folding.
  • A shape has only one net.
    Most shapes have several.

Your turn

  • 1. How many faces does a net of a cube have?
  • 2. What shapes make a net of a square pyramid?
Show answer

1. 6 2. 1 square and 4 triangles

Summary

What to take away

  • A net shows every face, laid flat.
  • Fold it in your head to test it.

More in Geometry

Parallel and perpendicular lines, and prisms5 minWhat is a Net? Fold 2D Shapes into 3D3 minNets, reflections, rotations and grid maps5 min

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