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Finding the surface area of spheres

Geometry · Grade 4–6

Strand: Geometry Substrand: Surface area Sparx code: U893 Sparx levels: 2, 3

Key steps (method)

  • Write down the relevant formula(s) for the shape(s) involved.
  • Convert units if needed (e.g. cm to m) before substituting.
  • Substitute carefully (use radius vs diameter correctly).
  • Calculate step-by-step and keep π on the calculator until the end if allowed.
  • Give the final answer with correct units (cm² for area, cm³ for volume).

Common mistakes

  • Mixing up radius and diameter (or forgetting to halve/double).
  • Using area units (²) when it’s volume (³), or vice versa.
  • Not converting units (e.g. mm² vs cm²).
  • Rounding π too early.

Quick notes

  • If you get stuck, try a simpler version of the problem first or plug in easy numbers to test your method.
  • For multi-step questions, label each step and keep intermediate results.
  • For exam questions, always aim to make your work “mark-scheme readable”.

Self-assessment

  • Can I define it? Write a one-sentence definition of Finding the surface area of spheres (or the key term in the question).
  • Can I do it? Do 3 questions: one easy, one standard, one harder. Don’t look at notes until you’ve tried.
  • Can I explain it? In 2–3 sentences, explain why the method works (or what would go wrong with a common mistake).
  • Can I check it? State one quick check (estimate, units, sign, reasonableness).

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Notes