Practical route session 8 · Finish retest and explain limits

Target: Finish retest and explain limits. Planning estimate: 50–65 min; add a continuation block if measurement or cleanup causes delays.

Print / prior evidence

Cool-water investigation: finish Retest trial sheets 2 and 3 (full student pages 11–12), then use Reassess the Redesign questions 1–2 and Evidence and Explanation questions 1–3 (pages 17–18). Teacher keys are on pages 15–17. Save the separate Later Reasoning Check, question 1 (page 19), for students who have not yet seen it.

Prerequisites: preceding collected evidence or the corresponding standalone kit bridge. The Cool-water investigation operational setup must be fully checked before handling.

Demonstration / learner work / collect

Run the remaining two fresh pairs (0/5/10 min), compare all retests with the identified reference, and account for drift, mismatch or missing data; use the supplied fallback if equipment is unavailable.

Next decision / continuation

Collect all raw records, a bounded result, revision and next test; clean up. Worse, negligible or variable outcomes are legitimate. Keep notes about actual physical work separate from the paper fallback.

No equipment homework or mandatory student internet access. Use the complete Cool-water investigation fallback for learners who do not handle equipment or when equipment is unsuitable; record that the fallback does not show construction or testing.