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Year 11 - Maths

Surface area of composite solids

2D and 3D shape: surface area and volume (pyramids, spheres and cones)

Unit Summary

In this unit, pupils will further develop their understanding of shapes by considering the surface area and volume of pyramids, spheres and cones.

Lesson Summary

You will learn to calculate the surface area of a composite solid.

Key Notes

  • The surface area of a composite solid is found by summing the area of all faces.
  • The faces may not always be the same shape.
  • The surface area may well be able to be calculated in a more efficient way.

Vocabulary To Learn

  • Surface area: The surface area is the total area of all the surfaces of a closed 3D shape. The surfaces include all faces and any curved surfaces.
  • Solid: A solid is a shape that has three dimensions (e.g. width, height and depth).
  • Compound shape: A compound shape is a shape created using two or more basic shapes. A composite shape is an alternative for compound shape.

Common Mistakes To Avoid

  • Pupils may not subtract overlapping faces from their surface area calculation.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

The surface area of a composite solid is found by summing the area of all faces. The faces may not always be the same shape.

2. Use this key word in a maths sentence and explain it clearly. 'Surface area'

The surface area is the total area of all the surfaces of a closed 3D shape. The surfaces include all faces and any curved surfaces. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Pupils may not subtract overlapping faces from their surface area calculation. Correction: Ask the pupils to visualise turning around/rotating the compound solid, and consider which faces of the component solids would always be hidden.

More Lessons In This Unit

Browse all guides in the Year 11 Maths guide library.