LAUNCH Science · W4L2 · lesson resources
Build a linked explanation
Choose one shared task or resource within the current lesson stage. Keep the lesson’s 40-minute timetable and 15-minute independent work.
We Do · Build a linked explanation
Point to the net direction for each gas. Then explain one adaptation.
| Gas | Alveolar air compared with arriving blood |
|---|---|
| Oxygen | Higher concentration |
| Carbon dioxide | Lower concentration |
Thin walls → what physical effect? → how does this help diffusion?
Discuss, point, write or dictate your first reason. Use one example first; extend only if there is time.
Reveal shared reasoning after an attempt
Oxygen: air → blood. Carbon dioxide: blood → air.
Thin walls give a short diffusion distance, so gases cross more quickly down their gradients. Blood flow and ventilation help maintain gradients.
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Model explanation and diagram
For each feature, say what it changes physically and why that affects diffusion. “Good lungs” is not an explanation.
Watch for: Both alveolar and capillary walls contribute to the diffusion path. Do not describe oxygen as choosing a destination.
Give a smaller support cue
Use three parts: the feature, what it changes, and how that affects diffusion. Start: “Thin walls help because…”
Optional video · Gas exchange in the lungs
Watch for: How does a thin wall help oxygen move into the blood?
Use a short relevant extract within I Do, then pause for an explanation. The clip replaces part of the modelling time.
Open the freesciencelessons video in a new tab
No-video version · use the same question
A thin wall gives a short diffusion distance. Oxygen moves down its concentration gradient from alveolar air into the arriving blood.
Internet is needed for the optional clip. It is concept teaching; viewing it is not completion of a practical.