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Goal: describe two valid model groupings by naming the rule each time, without silently moving between rules. Proposed codes: AC9SFU01 (model reasoning), AC9SFI03, AC9SFI05. Prepare: N1–N4, pointed sort, revision board, Card 146.
Source · 3 min. Restore FICTIONAL MODEL label and four drawings; leave actual logs apart.
Recall · 4 min. Rebuild the pointed-versus-rounded outline groups from Day 142.
New rule · 5 min. State “stem-and-leaf marks visible / leg marks visible.” N1/N2 and N3/N4 now form different pairs because the rule changed.
Child try · 7 min. Card 146 routes compare the two sorts and say which observable feature each used; do not say one grouping is universally correct.
Probe · 4 min. Ask, “Did N2 change?” Child explains the drawing stayed the same while the question changed.
Exit · 2 min. Save both rule labels and memberships, clearly marked as model examples.
