Codes: AC9M7N06, AC9M7N09, AC9M7N05. Goal: formulate and check a practical rational-number calculation. Prepare: fictional $120 event brief; no real purchase or club funds.
- Read · 2 min. “A fictional community event has $120 for two listed costs: $38.40 transport and $46.75 materials. How much remains?” Ask what quantities are known and unknown.
- Estimate · 5 min. Approximate
$120 − $40 − $47 ≈ $33; label estimate. Say exact remainder should be near this, not negative or above $120. - Model · 6 min. Add costs:
$38.40 + $46.75 = $85.15; subtract$120.00 − $85.15 = $34.85. Check$85.15 + $34.85 = $120.00. State $34.85 remains and that a budget does not tell us whether the event is worthwhile. - Partner alternative · 7 min. Pairs use a different valid strategy, e.g. subtract transport first:
$120 − $38.40 = $81.60; then$81.60 − $46.75 = $34.85. Ask which steps are easy to explain to a committee reader. A calculator can verify after the two methods are visible. - Interpret · 3 min. Ask: “Can we add another $40 item?” No, not within $34.85 remaining. Ask what else a real organiser would need to know; do not invent tax or prices.
- Exit · 2 min. Everyone gives remainder with unit and one check. Focus learners explain why the rounded estimate differs from the exact answer.
Access: read-aloud brief, line-by-line text, screen-reader-friendly amounts, paper tokens if helpful. No student or family financial data.