Useful job: Choose relevant matching details for a material or action question.
Target opportunity: AC9S1U03 / AC9S1I01 / AC9S1I04 / AC9S1I05 / AC9S1I06. Complete ordinary sources: C15/C16; their full original fictional bodies and separate worked/next accounts are in ORDINARY.md. Use the full curriculum/reference module for scope; code labels are not attained criteria.
Six teaching moves
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Read C15’s material-comparison question and all its matched/changed details. Ask what was deliberately different before deciding whether the comparison fits.
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Let the child explain one relevant match and one observed difference. Material need not be identical when material is the question; exact force was not measured.
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Model different C16’s strength question with equal drawn-space units. The same count alone does not establish measured force or all future movement.
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Choose a question-switch, a caption workshop or a wanted future comparison plan. No two-material purchase or actual experiment is required.
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Invite one fitting next comparison that names its intended change and at least one relevant match. A paper card or spoken plan helps memory without becoming a compulsory checklist.
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If several changes are attributed to one material, ask what more would separate them. If no extra difference is reported, keep that honest result. Never demand a fault merely because the exercise asks about fairness.
Three engagement choices
Route58.1 · Switch the question. Using C15, first ask about paper versus cloth resting shape, then ask about push strength. Child says why the same supplied record is useful for the first and insufficient for the second. Both source records remain intact.
Route58.2 · Caption workshop. Read C16 and the new overclaim “The equal finishes prove the pushes had exactly equal strength.” Child narrows it to recorded finishes under stated conditions; exact strength remains unknown.
Route58.3 · Plan a useful pair. Child chooses material or action as a question for a future small game. Name the intended change, a relevant match and an honest remaining limit. Adult checks any later actual option; no performed-investigation evidence is inferred.
Small check: Explains why matches serve the chosen question, retaining the intended change and unmeasured/unsupplied limits.
Targeted next teaching: Use C15’s stated material difference when “fair means same material” appears, or C07’s labelled action variation for strength-label confusion.
Finish invitation: “Would you keep this, change something, ask a question, or finish?”