Area of 2D and 3D Shapes

Students learn how to calculate the area of triangles, parallelograms and trapeziums.  They use this knowledge to later find the total surface of cuboids and prisms.

This topic takes place in Term 2 of Year 8 and is the prerequite topic for Circles, Cylinders and Circular Shapes.


Area of 2D and 3D Shapes Lessons
Prerequisite Knowledge
  • Derive and apply formulae to calculate and solve problems involving: perimeter and area of triangles, parallelograms, trapezia, volume of cuboids (including cubes) and other prisms
  • Calculate and solve problems involving: perimeters of 2-D shapes and composite shapes.
Key Concepts
  • The area of a triangle is the product of its perpendicular height and base divided by two.  Students often forget to divide by two.
  • To find the area of a composite shapes students should break it down into its individual components.
  • When identifying individual components of a composite shape students tend to look for triangles and rectangles rather than trapezia and parallelograms.
  • To find the surface of a cube or cuboid students could draw the net and work out the composite area.
  • More able students could derive the formula for the surface are of a cuboid.
Working mathematically

Develop fluency

  • Use language and properties precisely to analyse 2-D and 3-D shapes

Reason mathematically

  • Begin to reason deductively in geometry,

Solve problems

  • Select appropriate concepts, methods and techniques to apply to unfamiliar and non-routine problems.
Subject Content

Shape

  • Derive and apply formulae to calculate and solve problems involving: perimeter and area of triangles, parallelograms, trapezia, volume of cuboids (including cubes) and other prisms
  • Calculate and solve problems involving: perimeters of 2-D shapes and composite shapes.

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