Standards: 5.NF.1, 5.NF.2 · Adding and subtracting fractions with unlike denominators, including mixed numbers

Part 1 — The Pour Station: two measuring cups as bar models (0–2 cups). The student picks “marks per cup” from candidate buttons (the two denominators, their product, the LCM, a near-miss like d+1, etc.). If either fraction lands between marks it’s flagged red and the pour is blocked with a why; when both land on marks, the third cup fills, the trade is written out, and the LCD is named (with a note when a bigger common denominator was chosen). Every successful pour ends with a benchmark taste test.
Part 2 — Taste-Test Estimator: 8 orders, each gated by a benchmark estimate (0/½/1) before the exact amount. Distractors target adding/subtracting across (2/5 + 1/2 = 3/7, 7/8 − 1/2 = 1), dropped regrouping, and flipped mixed-number subtraction — each rejected with benchmark reasoning.
Part 3 — Common Denominator Machine (benchmark → multiples lists → trade via ×k/k → numerators only → simplify/check), Mixed Number Machine (estimate by wholes → match fraction parts → add with carry or subtract with borrow-a-whole → add-back check), Reasonableness Machine (sum ≥ each part, two-halves bounds, add-across detection, add-back for differences → verdict vs exact).
Part 4 — Quiz, tiers: Head Chef / Sous Chef / Line Cook / Kitchen Trainee.

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