A changed start
Made-up practice story.
A fictional plan uses a covered tray with 40 mL inside and an uncovered tray with 20 mL outside. Can it isolate the cover effect? Repair it.
Make something useful
Use a small caption, arrow model, table or spoken explanation for this exact question. Keep the supplied story beside you.
Grown-up help
Worked practice: No. Match starting volume and place (as well as tray and review duration), then change only the cover status. Do not predict a fixed visible loss from the repaired plan.
Complete Day 36 plan. This is ordinary practice, not a held assessment source.