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Day 8 — The location changed the answerYear 8 Maths · T1 W1–2 · Day 8 lesson

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Year 8 / Term 1 / Weeks 01 02 / Mathematics

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

Open for this lesson: Sources and materials · Check guide.

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Success: critique a convenience sample without calling its arithmetic wrong. (AC9M8ST01, AC9M8ST02, AC9M8ST04)

  1. See · 2 min. Display rack C: 16 bicycles out of 20; ask for its sample percentage.
  2. Model · 4 min. 16/20=80%, which is correct for C. Because selection was beside racks, it may overrepresent cyclists; it cannot estimate all students well.
  3. Guided compare · 5 min. Contrast C's 80%, random model A's 15%, B's 20% and known fictional population's 20%. Ask which source answers each narrower question.
  4. Independent critique · 7 min. Learners write a two-line correction to “80% of all students cycle”: valid sample result plus uncertainty about population.
  5. Fairness talk · 4 min. Ask why a shelter decision based on the rack sample could overlook bus users. Do not ask anyone to disclose their own travel.
  6. Exit · 3 min. “What is wrong: 16/20=80% or calling that 80% of all students?” Key: the population inference.

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