Teacher copy: This page may include teaching prompts or answer keys. Answer keys in this public library can be viewed by anyone. Give learners a clean prompt, use checks as formative evidence, and change a case locally when prior access matters.
Goal: plan one surface change and steady drop method, wait and viewpoint in a safe comparison. Proposed codes: AC9SFU03, AC9SFI01, AC9SFI05. Prepare:surface plan, D setup, broad fixed labels, Card 112.
Safety gate · 3 min. Adult confirms or declines local approval, known large materials, catch tray and cleanup; no child handles water.
Read · 4 min. Name plain paper and plastic mat as the planned surface difference; keep drop method/wait/view the same in the plan.
Model confound · 5 min. Adult changes a paper WAIT card for one imagined surface and shows why that adds a second difference.
Child try · 7 min. Card 112 routes select same/change labels and an interruption rule for run-off or spill; no paper diagram becomes a real test.
Check · 4 min. Ask whether a large drop on one sheet and a tiny drop on the other isolates surface. Child identifies drop amount as another change.
Exit · 2 min. Save child-controlled plan and adult safety decision.
