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Maths for SG Primary Schools

Primary 4 maths · Geometry · About 10 minutes

Recognise nets of cubes, cuboids, prisms and pyramids

Count hidden as well as visible faces and follow their shared edges.

Start the interactive lesson →Open practice activity

What you will learn

Models used: number sentences, stories, diagrams.

Before you start

From flat faces to a solid

A cube has six square faces. Some are hidden when we look from here.

  1. A cube has six square faces. Some are hidden when we look from here.

    A new view can hide or reveal faces without changing the solid. A net must reconnect all faces without gaps or overlaps.

    A cube with three visible and three hidden faces
  2. The flat shapes are the faces of a cube. The joined edges are the folds.

    Imagine opening the edges and laying every face flat. This is a net.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
  3. Fold the squares along their joins. Each face meets its neighbours to close the cube.

    All six faces close without gaps
What did the picture help us see?

Fold the squares along their joins. Each face meets its neighbours to close the cube.

Worked example: A new example, together

Which solid can be formed by folding this net?

Fold along shared edges. Faces close the solid without overlaps or gaps.
  1. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    Count hidden as well as visible faces and follow their shared edges.

    Each face of a solid appears once in its net and must meet the neighbouring faces correctly.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
  2. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    Count and name the faces.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
    Which solid can be formed by folding this net?

    triangular prism

  3. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    Count and name the faces.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
  4. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    Two matching triangles and three rectangles close a triangular prism.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
  5. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    The solid is a triangular prism.

    Fold along shared edges. Faces close the solid without overlaps or gaps.
  6. The flat shapes are the faces of a triangular prism. The joined edges are the folds.

    Check the result against the question we started with.

    Check that every edge pairs up and faces do not overlap.

    We found triangular prism. Each face of a solid appears once in its net and must meet the neighbouring faces correctly.

    Fold along shared edges. Faces close the solid without overlaps or gaps.

Common mistakes to discuss

Check your understanding

Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.

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