Wanted outcome: one accurate comparison with unit, start, end and duration. Prepare: O2 and paper grid, counters or calculator if useful.
0–3: Ask whether “A is 38 mm” means it grew 38 mm. 3–9 model: start 20, final 38, so increase 38 − 20 = 18 mm over nine days. B increases 6 mm; A’s increase is 12 mm greater. Both have 4 of 4 alive at Day 9. This is not a claim that they remain alive. 9–21: choose a route. 21–27: check units/time and mark a sentence that would overclaim cause. 27–30 exit: “Which difference concerns growth, and which concerns survival?” Reteach with separate height/count columns if blended.
- Route 2A · Change table. Calculate each group’s increase at Days 3, 6 and 9 from Day 0. Show A: 6, 12, 18 mm; B: 2, 4, 6 mm. Add an alive-at-Day-9 row and explain why no earlier survival trend can be drawn from a single final count.
- Route 2B · Two-line graph. Create labelled axes day 0–9 and height 0–40 mm, using equal day intervals 0/3/6/9. Plot every O2 point with distinct labels or line patterns. State the recorded pattern and a limit: these are supplied mean records; joining points does not reveal unmeasured moments.
- Route 2C · Claim audit. Audit “A gained 38 mm”, “shade killed B”, “both groups had four alive at Day 9”, “A’s mean increased more in this record”. Replace the first with 18 mm; reject the second; retain the last two with attribution. Give one question about a missing condition.