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Goal: solve Card H by two exact routes and reject an invalid sum rule. Say: “Different valid routes should meet at the same value.”
0–2: Recall the false rule from Day 4.
2–7: Model only sqrt(18)=3sqrt(2) and sqrt(8)=2sqrt(2).
7–13: Pairs finish numerator-first and term-by-term division routes.
13–20: Independently identify the invalid step in sqrt(26)/sqrt(2) and approximate-check the correct result.
20–25: Compare routes; note that exact simplification reaches a whole number here by design.
Routes: write both routes; orally compare routes with a teacher capturing both equalities; arrange radical tiles above and below a fraction bar then label the cancellation. Other domains:Day 8 swaps. Optional/home: invent a numerator of two like surds over one matching surd that simplifies to 6. Move: if a student says the incorrect draft is “close enough”, estimate sqrt(26)/sqrt(2)=sqrt(13), which is below 4, while the true answer is 5.