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LAUNCH · GCSE Biology · Week 4 · Introduce

Diffusion: Net Movement Down a Gradient

🎯 Learning objective: I can explain diffusion as net movement down a concentration gradient and identify factors affecting rate.
✅ Success criteria
  • Use net movement and higher→lower concentration.
  • State diffusion is passive.
  • Explain effects of gradient, temperature, surface area or distance.
ArrivalStarterI DoWe DoI Do 2We Do 2IndependentExit
🧬 Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1🧪 Particle Evidence Chamber⏱ 40 minutes
🫁
Introduce → Particle Evidence Chamberobserve · predict · test · explain · apply
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION
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.
⏱ 4 min
🚪 Arrival · previous learning
Retrieve the previous learning: W3 cells/membranes and precise GCSE terminology.
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 units you wrote in your answer.

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 solved magnification problems. Why did the units have to match?

R2 Week 3

Say which lens is closest to the specimen.

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?

R3 Week 3

Point to something you could only see with a microscope.

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?

Lead-in Into today

Someone opens perfume at the front. Point to where you would smell it first.

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Perfume opened at the front of the room reaches the back with nobody fanning it. How?

▲ Standard — three retrieval questions and one lead-in
R1 Last lesson

Last lesson you solved magnification problems. Why did the units have to match?

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Last lesson: explain how you checked whether your answer was sensible.

R2 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: a light microscope has a limit. Explain why magnification cannot get past it.

R3 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: cells are small. Say why that matters for how substances get in and out.

Lead-in Into today

Perfume opened at the front of the room reaches the back with nobody fanning it. How?

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Particles move randomly in all directions, yet the smell spreads one way overall. Explain how both can be true.

★ Stretch — three retrieval questions and one lead-in
R1 Last lesson

Last lesson: explain how you checked whether your answer was sensible.

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 units you wrote in your answer.

R2 Week 3

Week 3: a light microscope has a limit. Explain why magnification cannot get past it.

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Say which lens is closest to the specimen.

R3 Week 3

Week 3: cells are small. Say why that matters for how substances get in and out.

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Point to something you could only see with a microscope.

Lead-in Into today

Particles move randomly in all directions, yet the smell spreads one way overall. Explain how both can be true.

Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Someone opens perfume at the front. Point to where you would smell it first.

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

Particles move randomly both ways. How can there still be an overall direction?

FRAME 1/4
WATCH RANDOM MOVEMENT
Pause for observation or prediction before advancing.
FRAME 2/4
FIND THE NET PATTERN
Pause for observation or prediction before advancing.
FRAME 3/4
CHANGE ONE RATE FACTOR
Pause for observation or prediction before advancing.
FRAME 4/4
EXPLAIN THE PATTERN
Pause for observation or prediction before advancing.

🎯 Commit to a prediction

Before we model it: once the smell has spread evenly, what are the particles doing?

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.
⏱ 5 min
👩‍🏫 I Do · model the reasoning
🧠 Teacher reasoning model — reveal only after the class has observed/predicted.
STEP Show random movement both ways, then reveal the thicker net arrow.
STEP Build the GCSE definition precisely.
STEP Make passive/no cell energy explicit.
✔ What this model helps us seeIt shows particles moving randomly and still producing a net movement from high to low concentration.
✘ What this model does not showIt leaves out what happens once the spread is even — the particles never stop, they keep crossing both ways, and the net movement simply falls to zero.
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 · hinge & response
Commit before reveal: Why can diffusion have a net direction if particles move both ways?
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 Steeper gradient, higher temperature and larger surface area can increase rate.
STEP Longer diffusion distance slows rate.
STEP Connect one factor to alveoli but save full gas exchange for Explore.
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 2 · scientific model / data
Interactive 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?

🫧 Diffusion rate lab

The model above reveals one explanation. This lab is button-only. It changes one factor at a time and works out a rate index live, so you can see which change speeds diffusion up.

Step 1 · Predict, before you test

Which change speeds up diffusion the most here: doubling the concentration difference, a little warming, or doubling the distance?

Choose one. Say it, point to it, or press it. Nothing here is right or wrong yet.

Step 2 · Test one factor at a time
Press one to test it.
Frozen results — these stay on the page

    Nothing tested yet.

    Step 3 · Explain
    SCIENCE GLITCH: “Particles move to where they are needed because the body tells them to.”

    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.
    ⏱ 10 min
    ✏️ Independent · evidence & transfer

    ✏️ Independent GCSE Biology

    Annotate the diffusion diagram. Then open the simulator. Pick one factor. Test it. Does the rate change? Now test a second factor. Write down the variable you changed. Write down the pattern you saw. Then explain it.

    🧪 PRACTICAL / EVIDENCE READY
    EquipmentParticle diagrams/counters; local simulator; optional teacher temperature demo.
    Safety / accessTeacher controls heat if used; lesson works without practical heating.
    Evidence targetAnnotated model + variable/pattern/explanation record.
    10 minutes. Supported / Standard / Stretch are movable routes, not grade identities.
    ◆ Finish the high→low diagram. Then test one variable.
    net movement · particles · high → low.
    Fade: remove the first prompt that no longer changes success.
    ▲ Test two variables. Then explain both patterns.
    Pattern → because frame.
    Fade: remove the first prompt that no longer changes success.
    ★ Explain how two factors work. Say what particles do. Particles move at random. Net movement is not the same.
    The simulator is only a model. It cannot prove every biological factor.
    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

    diffusion
    concentration gradient
    net movement

    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

    Diffusion moves overall from high to ___.

    ▲ Standard

    Name two factors increasing rate.

    ★ Stretch

    Explain why a thin barrier speeds diffusion.

    🔁 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.
    🧑‍🏫 LAUNCH SUPPORT STAFF · THIS SLIDE

    ONE SCIENCE RULE

    ‘Things spread out’ is not enough. Push to net movement and concentration gradient.

    Priority now

    Move learning forward

    Least prompt first
    waitself-promptvisual cuegeneral verbalspecific verbalmodeldirect support

    Move right only as needed, then fade back left.

    🔁 LAUNCH LIVE FEEDBACK–RESPONSE LOOP

    Scientific response changes what happens next

    SPACE

    Stable seating/adult, clear deadlines, no public grading, processing time and authorised access arrangements.

    VOICE

    In-lesson edit, structured verbal response, calculation, graph/data interpretation, demonstration or re-attempt.

    AUDIENCE

    Adult genuinely engages with the edit/re-attempt against the scientific model/criteria.

    INFLUENCE

    Next instruction, question, scaffold, retrieval plan or mock preparation changes because of the response.

    Read the response — classify the cause, not the learner

    Read/listen first. The response decides the next teaching move.

    Policy code reference · staff side only

    VF · verbal feedbackWS · worked with supportI · independentNS+ · one next stepE · evidenceR · responded / Audience happened// · self-edit? · read back

    No code or pupil response is stored by this HTML. No public marks, grade boards or comparison.

    LAUNCH GCSE Biology · W4L1 · Diffusion: Net Movement Down a Gradient

    Name: _______________________________   Date: ______________________

    Not here last lesson? Everything you need is in the Retrieval box below — read it, then answer.

    Learning objective: I can explain diffusion as net movement down a concentration gradient and identify factors affecting rate.

    Retrieval: W3 cells/membranes and precise GCSE terminology.

    R1 · Last lesson: Last lesson you solved magnification problems. Why did the units have to match?

    R2 · Week 3: Week 3: what is the difference between magnification and resolution?

    R3 · Week 3: Week 3: why do we measure cells in micrometres?

    Lead-in · Into today: Perfume opened at the front of the room reaches the back with nobody fanning it. How?

    Supported

    ◆ Complete high→low diagram and test one variable.

    net movement · particles · high → low.

    Standard

    ▲ Test two variables and explain both patterns.

    Pattern → because frame.

    Stretch

    ★ Explain two factors mechanistically and distinguish random from net movement.

    Do not claim the simulator proves every biological factor.
    What this model helps us see: It shows particles moving randomly and still producing a net movement from high to low concentration.
    What this model does not show: It leaves out what happens once the spread is even — the particles never stop, they keep crossing both ways, and the net movement simply falls to zero.
    WORD HELP
    diffusion — spreading out from where there is more to where there is less
    concentration gradient — the difference between a more crowded area and a less crowded one
    net movement — the overall direction once both ways are counted

    Evidence target

    Annotated model + variable/pattern/explanation record.

    Exit + feedback response

    Supported: Diffusion moves overall from high to ___.

    Standard: Name two factors increasing rate.

    Stretch: Explain why a thin barrier speeds diffusion.

    Response on this same work: I changed / next I will _________________________________________

    Adult genuinely receives the response. No signature/initial is required.

    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: