LAUNCH · GCSE Biology · Week 4 · Explore
Diffusion in the Lungs
🎯 Learning objective: I can apply diffusion to alveoli and use evidence to explain rapid gas exchange.
✅ Success criteria
- State O₂ and CO₂ directions.
- Link alveolus adaptations to diffusion factors.
- Use an observation/result as evidence.
ArrivalStarterI DoWe DoI Do 2We Do 2IndependentExit
🧬 Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1🧪 Gas Exchange Evidence Lab⏱ 40 minutes
🫁
Explore → Gas Exchange Evidence Labobserve · predict · test · explain · applyQUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Stable conditions and clear expectations make GCSE thinking possible.
⏱ 3 min
🚪 Arrival · previous learningRetrieve the previous learning: W4L1 definition and rate factors. Diffusion is the net movement of particles from higher to lower concentration.
Not here last lesson? Everything you need is in the box above — read it, then answer.
◆ Supported — three retrieval questions and one lead-in
R1 Last lesson
Point to the crowded side of the diagram.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Last lesson you defined diffusion. Which way is the net movement?
R2 Week 3
Say what a microscope helps you see.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Week 3: why do we measure cells in micrometres?
R3 Week 3
Point to the eyepiece.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Week 3: what is the difference between magnification and resolution?
Lead-in Into today
Look at the lung diagram. Point to the air sacs.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Your lungs hold millions of tiny air sacs instead of two big bags. Why so many small ones?
▲ Standard — three retrieval questions and one lead-in
R1 Last lesson
Last lesson you defined diffusion. Which way is the net movement?
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Last lesson: name two factors that change how fast diffusion happens, and say why.
R2 Week 3
Week 3: why do we measure cells in micrometres?
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Week 3: explain how a microscope let biologists see the structures we are about to explain.
R3 Week 3
Week 3: what is the difference between magnification and resolution?
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Week 3: resolution decides what detail you can report, not magnification. Explain why.
Lead-in Into today
Your lungs hold millions of tiny air sacs instead of two big bags. Why so many small ones?
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Predict which features of an exchange surface would make diffusion fastest, and say why for each.
★ Stretch — three retrieval questions and one lead-in
R1 Last lesson
Last lesson: name two factors that change how fast diffusion happens, and say why.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Point to the crowded side of the diagram.
R2 Week 3
Week 3: explain how a microscope let biologists see the structures we are about to explain.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Say what a microscope helps you see.
R3 Week 3
Week 3: resolution decides what detail you can report, not magnification. Explain why.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Point to the eyepiece.
Lead-in Into today
Predict which features of an exchange surface would make diffusion fastest, and say why for each.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Look at the lung diagram. Point to the air sacs.
Arrival retrieves three times, then leads in. R1 is last lesson, R2 is the previous week, R3 is older material, and the lead-in opens today without teaching today’s concept.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Quiet retrieval before new demand; uncertainty is information, not public failure.
⏱ 4 min
🌱 Starter · observe / predict🔍 Scientific question
An alveolus is tiny, thin and wrapped in capillaries. Why spend so much structure on making gas exchange fast?
FRAME 1/4
PREDICT GAS DIRECTION
Pause for observation or prediction before advancing.
FRAME 2/4
REVEAL ADAPTATIONS
Pause for observation or prediction before advancing.
FRAME 3/4
COLLECT EVIDENCE
Pause for observation or prediction before advancing.
FRAME 4/4
LINK EVIDENCE TO DIFFUSION
Pause for observation or prediction before advancing.
🎯 Commit to a prediction
Before we look: what would speed up diffusion at an exchange surface?
Choose one. Say it, point to it, or press it.
Nothing here is right or wrong yet, and nothing is marked, scored or stored. A prediction is still worth having when it turns out differently — that is what makes the test worth running.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Prediction/observation precedes explanation.
⏱ 4 min
👩🏫 I Do · model the reasoning🧠 Teacher reasoning model — reveal only after the class has observed/predicted.
STEP Build the alveolus structure visually before arrows.
STEP Ask pupils to predict O₂/CO₂ direction, then reveal.
STEP Link large area, thin wall and blood flow to diffusion rate.
✔ What this model helps us seeIt shows the alveolus and the capillary side by side, so the gradient and the short distance are visible at once.
✘ What this model does not showIt leaves out the scale — a real alveolar wall is a fraction of the thickness this drawing can show, and that thinness is doing much of the work.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Teacher models scientific reasoning; staff watch access and the point where the idea lands.
⏱ 4 min
🤝 We Do · hinge & responseCommit before reveal: Why does good blood supply help diffusion?
Answer first. The reveal is earned by the response, not by a timer.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Adult genuinely receives the response; the next question, explanation or scaffold changes because of it.
⏱ 4 min
👩🏫 I Do 2 · connect / extend🧠 Teacher reasoning model — reveal only after the class has observed/predicted.
STEP Optional limewater evidence: cloudy is a positive CO₂ test.
STEP Breathed-out air may cloud limewater faster because it contains more CO₂.
STEP Breathing/exercise is never compulsory; timing/recording/data routes are valid.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Teacher models scientific reasoning; staff watch access and the point where the idea lands.
⏱ 5 min
🤝 We Do 2 · scientific model / dataInteractive reasoning: predict/observe first → use the model → explain the evidence → adult receives it.
🧪 Scientific reasoning model
🫁
Prediction / observation first. Then use the reveal.
What do you notice or predict before revealing the explanation?
🫁 Alveolus evidence lab
The model above reveals one explanation. This lab is button-only. It changes one alveolus feature at a time and works out an exchange index live, so the explanation is built from evidence.
Step 1 · Predict, before you test
Which feature does most for FAST gas exchange in the alveolus?
Choose one. Say it, point to it, or press it. Nothing here is right or wrong yet.
Step 2 · Test each feature
Press one to test it.
Frozen results — these stay on the page
Nothing tested yet.
Step 3 · Explain
SCIENCE GLITCH: “Oxygen crosses into the blood because the lungs push it through the wall.”
Use your frozen list as the evidence. Decide, then say why.
Every step is a button, and each option carries a shape and a word as well as its colour. Say it, point to it or have an adult press it — the route does not change the Biology.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Adult genuinely receives the response; the next question, explanation or scaffold changes because of it.
⏱ 12 min
✏️ Independent · evidence & transfer✏️ Independent GCSE Biology
Pick one route. Do the practical. Or use the diagram and data. Write your prediction first. Write what you saw. Then explain it. Link your evidence to diffusion. And to alveolus structure.
🧪 PRACTICAL / EVIDENCE READY
EquipmentAlveolus model/diagram; optional limewater apparatus under local risk assessment; timers/table.
Safety / accessNo pupil is required to breathe into apparatus or exercise. Follow local chemical/hygiene procedures.
Evidence targetAnnotated alveolus + result/observation + pupil explanation.
12 minutes. Supported / Standard / Stretch are movable routes, not grade identities.
◆ Label the adaptations. You get limewater observations. Say what they show.
Adaptation → diffusion factor matching.
Fade: remove the first prompt that no longer changes success.
▲ Watch or run the safe demo. Record the result. Explain two adaptations.
Result → conclusion → diffusion reason.
Fade: remove the first prompt that no longer changes success.
★ Explain the adaptations. Find one limit in the method. Evaluate it.
Judge the evidence first. Then give the biological explanation. Keep them apart.
Fade: remove the first prompt that no longer changes success.
1 · Learner decisionprediction, plan, command-word choice or calculation set-up
2 · Observable Sciencemeasurement, graph, working, model, practical result or answer
3 · Learner responseexplanation, evaluation, edit or re-attempt after feedback
📖 WORD HELP
alveolithe tiny air sacs in the lungs
diffusionspreading out from where there is more to where there is less
concentration gradientthe difference between a more crowded area and a less crowded one
Use the Biology word first. Ask for help only when you need it. TA fade route: model the word. Then prompt for it. Then wait for it. Drop a step as soon as the pupil no longer needs it.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Pupil reasoning stays attributable; feedback produces an edit, re-attempt, calculation, explanation or application.
⏱ 4 min
🎫 Exit · receive and use the response◆ Supported
Which gas diffuses into blood?
▲ Standard
Explain one alveolus adaptation.
★ Stretch
Explain how thin wall and blood flow work together.
🔁 LAUNCH Lundy close — use the existing work
1) Pupil answers / edits / re-attempts. 2) Adult genuinely reads, listens or watches and names back what was received. 3) Where appropriate, the pupil adds the single response/next-step line on the same work: “I changed / next I will …”
No adult signature/countersignature. If local policy uses R, it follows genuine Audience only; this page never adds it automatically.
Closing the loop: this one ends on paper — your own hand, or your words scribed by an adult. Saying it aloud starts the loop; writing it is what closes it. Pass is always allowed.
What I said, and what it changed:
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate🔁 re-attempt
Access changes the response route, not the GCSE Biology entitlement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
LAUNCH rule: the explanation is earned by observation, prediction, measurement, testing or reasoning from evidence.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
LAUNCH response stays on the existing work; adult genuinely receives it, then the next learning move changes.