LAUNCH · GCSE Biology · Week 5 · Introduce
Osmosis: Water Across a Membrane
🎯 Learning objective: I can define osmosis and explain how water movement depends on a partially permeable membrane.
✅ Success criteria
- Define osmosis precisely.
- Identify dilute/concentrated in terms of water.
- Distinguish osmosis from general diffusion.
ArrivalStarterI DoWe DoI Do 2We Do 2IndependentExit
🧬 Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1🧪 Membrane Reasoning Lab⏱ 40 minutes
💧
Introduce → Membrane Reasoning 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.
⏱ 4 min
🚪 Arrival · previous learningRetrieve the previous learning: W4 diffusion down a gradient with no cell energy. Diffusion is the net movement of particles from higher to lower concentration, down a gradient, with no cell energy.
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 word diffusion on the card.
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 wrote diffusion explanations. What must a good explanation link?
R2 Week 4
Say which way particles spread.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — Week 4: define diffusion, and name one factor that changes its rate.
R3 Week 3
Point to the lens you look through.
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 does resolution mean?
Lead-in Into today
Look at the two sides of the bag. Point to the side with more water.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Standard — A membrane lets water through but blocks sugar. Predict which way the water moves.
▲ Standard — three retrieval questions and one lead-in
R1 Last lesson
Last lesson you wrote diffusion explanations. What must a good explanation link?
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Last lesson: an answer needs direction, gradient and adaptation. Explain how they combine.
R2 Week 4
Week 4: define diffusion, and name one factor that changes its rate.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — Week 4: explain why a thin, large exchange surface speeds diffusion up.
R3 Week 3
Week 3: what does resolution mean?
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 why we needed microscopy before we could explain membranes at all.
Lead-in Into today
A membrane lets water through but blocks sugar. Predict which way the water moves.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Stretch — If only water can cross, explain what happens to the concentrations on both sides over time.
★ Stretch — three retrieval questions and one lead-in
R1 Last lesson
Last lesson: an answer needs direction, gradient and adaptation. Explain how they combine.
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 word diffusion on the card.
R2 Week 4
Week 4: explain why a thin, large exchange surface speeds diffusion up.
Non-reading route: point to it, say it, or show it. An adult can scribe your exact words. Next step up: Supported — Say which way particles spread.
R3 Week 3
Week 3: explain why we needed microscopy before we could explain membranes at all.
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 lens you look through.
Lead-in Into today
If only water can cross, explain what happens to the concentrations on both sides over time.
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 two sides of the bag. Point to the side with more water.
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
A membrane lets water through but blocks sugar. If one side has more water and one less, which substance can change sides?
FRAME 1/4
IDENTIFY WHAT CAN CROSS
Pause for observation or prediction before advancing.
FRAME 2/4
COMPARE WATER BOTH SIDES
Pause for observation or prediction before advancing.
FRAME 3/4
PREDICT NET MOVEMENT
Pause for observation or prediction before advancing.
FRAME 4/4
BUILD GCSE DEFINITION
Pause for observation or prediction before advancing.
🎯 Commit to a prediction
Before we test: water can cross, sugar cannot. Which way does water move overall?
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 Reframe by water: dilute = more water; concentrated = less.
STEP Show water moving both ways with net movement.
STEP Make membrane selectivity essential.
✔ What this model helps us seeIt shows a membrane that lets water through and holds larger molecules back, so the direction of water movement follows from the picture.
✘ What this model does not showIt leaves out that the membrane is not a simple sieve — it is a living structure, and the model makes it look like a fixed mesh.
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 & responseCommit before reveal: Which substance moves by osmosis?
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 Build the full four-part definition.
STEP Connect osmosis back to diffusion of water.
STEP Correct ‘water moves to sugar’ by reframing with water concentration.
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 / 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?
🚪 Membrane gate lab
The model above reveals one explanation. This lab is button-only. It counts water crossings through a partially permeable membrane in three set-ups, so the definition of osmosis comes from evidence, not from being told.
Step 1 · Predict, before you test
A cell sits in PURE WATER. Which way is the net water movement?
Choose one. Say it, point to it, or press it. Nothing here is right or wrong yet.
Step 2 · Test each set-up
Press one to test it.
Frozen results — these stay on the page
Nothing tested yet.
Step 3 · Explain
SCIENCE GLITCH: “The membrane lets everything through, so anything can cross.”
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. The crossing counts are fixed example numbers, the same for every pupil.
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
Look at both scenarios. Label each one. Then use the membrane model. Which way does water move? Predict it. Write the full definition. Then explain one result.
🧪 PRACTICAL / EVIDENCE READY
EquipmentMembrane/water/solute diagrams or counters; local model.
Safety / accessNo practical hazard; precision matters more than speed.
Evidence targetAnnotated scenarios + precise definition + one explanation/re-attempt.
10 minutes. Supported / Standard / Stretch are movable routes, not grade identities.
◆ Label the dilute side. Then the concentrated side. Complete the definition.
Use the four key phrases. Tick each one.
Fade: remove the first prompt that no longer changes success.
▲ Write the definition. Do it alone. Then explain two diagrams.
Describe both sides. Then give the direction.
Fade: remove the first prompt that no longer changes success.
★ Compare osmosis and diffusion. Say what is the same. Then what differs.
Say net movement. Say membrane selectivity. Be precise.
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
osmosiswater moving across a partially permeable membrane towards the stronger solution
partially permeablelets some things through but not others
membranethe thin layer around a cell
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
Osmosis is movement of ___.
▲ Standard
Why does sugar not cross?
★ Stretch
Why is osmosis a special case of 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.