Job: choose a repeatable blocker-position comparison for the child's purpose. Ready: same approved setup or ordinary change-one model; positions chosen locally. Say: “What shall we change? What stays?”
- 0–3: Choose a question about the blocker, such as whether moving it while keeping the same source and screen changes the visible shadow. Accept another investigable question and name a relevant outcome to notice.
- 3–8: Before diagrams, offer a short actual baseline shadow look. Agree source, screen, blocker size/orientation and what position reference can be kept. No real distance comes from the diagram. Name learner/adult operators.
- 8–12: Predict a possible effect and reason. If useful, encounter the ordinary change-one idea model (bar4→2, screen8 fixed); it is not held C/D and not actual data. The learner can use a qualitative relation rather than numbers.
- 12–20: Optionally perform the chosen comparison and repeat a useful part under agreed conditions. An adult can move the blocker; the learner can observe/direct/record. If an edge is unclear, choose a qualitative description or stop. If the lamp/screen also moved, retain that fact and avoid a single-variable conclusion.
- 20–25: Keep one actual available finding or an unperformed plan. Ask what would help another try. First predictions remain separate from observations, and a changed prediction is welcome. Prepare held C privately for Day25.