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Day 17 · The GST base changes with the price labelYear 11 Maths · T1 W3–4 · Day 17 lesson

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Year 11 / Mathematics / Term 1 / Weeks 03 04

Part of the full two-week lesson sequence. Check the pack guide and taught point before teaching.

Open for this lesson: Pack guide · Fresh learner checks · Aids and text routes.

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Teacher copy: This page may include teaching prompts or answer keys. Answer keys in this public library can be viewed by anyone. Give learners a clean prompt, use checks as formative evidence, and change a case locally when prior access matters.

Learner choices

Goal: calculate included and excluded GST in explicitly fully taxable fictional supply examples. 25 = 2 + 5 + 6 + 7 + 5.

  1. 0–2: Read Card E's condition fully taxable and the ATO-source note. The 10% rate is verified for a taxable supply; a real item's treatment needs its own check.
  2. 2–7: Model $84 excluding GST: $84×0.10=$8.40; inclusive $92.40. Check 84×1.10=92.40.
  3. 7–13: For $121 including GST, model reversal 121÷1.10=$110 exclusive, GST $11; check 110+11=121. Explain why $121−10%×121 uses the wrong base.
  4. 13–20: Routes: move base/tax/total blocks with labelled denominators; complete the price-base ladder; write/spoken calculation with factor 1.10 and reverse addition. Each route states the fully-taxable assumption and no real classification claim.
  5. 20–25: Exit “Is 10% of $121 the included GST?” Key: no; for this fully taxable example it is $11, one eleventh of inclusive price. Move: reconstruct base×1.10=total with $110 before a shortcut.

Alternative domain: Fictional adult poster-print supply. Optional/home: under an explicitly fully taxable invented example, find inclusive $55 from exclusive $50; no shopping task.

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