Opening

LAUNCH · SCIENCE · Lesson 5 of 7

Can the claim survive the evidence?

Learning intention

Use evidence about control, circulation and gas exchange to judge claims in an unfamiliar model.

A fictional teaching lab has three connected models.

Your job: calculate, explain and limit its claims.

Success looks like

Calculate and compare pump output with units.
Use a controlled comparison to explain a diffusion prediction.
Separate a supported mechanism from a claim the data cannot establish.

Retrieval

LAUNCH · SCIENCE · Lesson 5 of 7

Recover three mechanisms

R1. What is cardiac output calculated from?

R2. Which way does net diffusion occur?

R3. Is insulin a signal or a glucose store?

I do

LAUNCH · SCIENCE · Lesson 5 of 7

Think across the oxygen pathway

Name the job at each link.

An output number describes one link only.

Oxygen supply is a linked pathway

Diagram description

Schematic pathway: ventilation replenishes alveolar air; oxygen diffuses into pulmonary blood; heart-driven circulation carries oxygen to tissue capillaries; oxygen diffuses towards cells down a gradient. Cells use oxygen in aerobic respiration. It is not a quantitative supply model.

I do

LAUNCH · SCIENCE · Lesson 5 of 7

Calculate before judging

A: 60 × 70 = 4,200 mL/min.

Convert: 4,200 ÷ 1,000 = 4.2 L/min.

Constructed pump records: calculate both factors

Diagram description

Constructed teaching records. Pump A: 60 beats/min × 70 mL/beat = 4,200 mL/min = 4.2 L/min. Pump B: 90 × 60 = 5,400 mL/min = 5.4 L/min. These are not observations of pupils or diagnostic reference ranges.

I do

LAUNCH · SCIENCE · Lesson 5 of 7

Keep signal and material separate

Insulin changes responses in target tissues.

Glucose is transported and can be stored as glycogen.

Distinguish a hormone message from a transported fuel

Diagram description

Two related but distinct routes. Insulin released by pancreatic beta cells is carried in blood and signals responsive target tissues. Glucose is carried as a material; insulin promotes uptake in responsive tissues and glycogen storage in liver/muscle. The model does not imply all glucose uptake requires insulin.

We do

LAUNCH · SCIENCE · Lesson 5 of 7

Choose a fair comparison

Go to interactive investigation

W1. Which pair tests area alone?

W2. Which pair tests thickness alone?

Constructed model: rate index = area × concentration difference ÷ thickness; same omitted constant.
Case	Relative area	Relative concentration difference	Relative thickness
X	3	4	1
Y	6	4	2
Z	6	4	1

My response — say it, sketch on paper or type

Systems evidence desk

Constructed classroom models: predict, test a claim, then explain its limit.

Decision 1 of 3

Which pump has the greater output in these records?

Choose, test, then explain together. Evidence diagrams appear only after your test. Diagram transitions explain the model; they do not represent real elapsed time. Use Pause model to stop transitions and model controls, or your device’s reduced-motion setting. The printed We do activity provides the paper route.

We do

LAUNCH · SCIENCE · Lesson 5 of 7

Audit the headline

W3. “B has a higher output, so every tissue definitely gets enough oxygen.”

Keep the supported part; reject the unsupported part.

Oxygen supply is a linked pathway

Diagram description

My response — say it, sketch on paper or type

We do

LAUNCH · SCIENCE · Lesson 5 of 7

Test a tempting shortcut

“Y has twice the area of X, so its index must be twice as large.”

Predict, calculate, then explain.

My response — say it, sketch on paper or type

Hinge

LAUNCH · SCIENCE · Lesson 5 of 7

Which conclusion is fully supported?

Select the claim that respects the evidence.

You do

LAUNCH · SCIENCE · Lesson 5 of 7

Write a defensible evidence note

Choose one route.

Include a calculation, a mechanism and a limit.

My response — say it, sketch on paper or type

You do

LAUNCH · SCIENCE · Lesson 5 of 7

Use the data; qualify the claim

Cite a named record or controlled pair.

Explain what the model cannot establish.

My response — say it, sketch on paper or type

Review

LAUNCH · SCIENCE · Lesson 5 of 7

Audience: ask for the missing evidence

L1. Share one claim with a quiet partner or adult.

Audience asks: what would you need to measure next?

My response — say it, sketch on paper or type

Review

LAUNCH · SCIENCE · Lesson 5 of 7

Make one claim stronger

Add a unit, a controlled comparison or a model limit.

My response — say it, sketch on paper or type

Exit

LAUNCH · SCIENCE · Lesson 5 of 7

Three quick evidence checks

E1. Calculate 80 beats/min × 50 mL/beat in L/min.

E2. Why is X/Y not an area-only test?

E3. Name one missing quantity for oxygen adequacy.

My response — say it, sketch on paper or type

Exit

LAUNCH · SCIENCE · Lesson 5 of 7

Choose the next practice

Units • controlled pairs • hormone roles • limits.

My response — say it, sketch on paper or type

Continue within this stage’s shared time.

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

Shared evidence | Constructed systems models

All records below are invented teaching data. They do not describe pupils or diagnose health.

Pump	Heart rate (beats/min)	Stroke volume (mL/beat)
A	60	70
B	90	60

Pump output = heart rate × stroke volume. There are 1,000 mL in 1 L. Neither oxygen content nor tissue demand was measured.

Exchange case	Relative area	Relative concentration difference	Relative thickness
X	3	4	1
Y	6	4	2
Z	6	4	1

Relative diffusion index = area × concentration difference ÷ thickness, using the same omitted constant. The rule is idealised and has no calibrated clinical unit.

Control case: glucose absorbed from the gut has raised blood glucose. Pancreatic beta cells release more insulin. Responsive tissues increase uptake and liver/muscle storage is promoted. This is a qualitative model, not treatment advice.

W1. Choose the area-only pair. W2. Choose the thickness-only pair. W3. Repair: “B has a higher output, so every tissue definitely gets enough oxygen.”

Supported route | Build an evidence note

Use the shared page. Sentence starters: “The calculation shows…”; “This comparison keeps…”; “It does not show…”.

S1. Calculate outputs for A and B in mL/min and L/min. Which is greater?S2. Choose the area-only pair from X, Y and Z. Name the two unchanged factors and predict the relative effect.S3. Explain how insulin differs from glucose and glycogen in the control case.S4. Repair: “A higher pump output proves enough oxygen reaches every cell.” Keep what is supported and state one missing measurement.

Standard route | Audit three claims

Use mechanisms and data in every answer where relevant.

M1. Calculate A and B outputs in L/min and the difference. Explain why comparing heart rate alone is unsafe as a general shortcut.M2. Calculate indices for X, Y and Z. Explain why X and Y do not isolate an area effect.M3. Explain the insulin response to raised blood glucose, distinguishing the hormone signal from the stored material.M4. Trace oxygen from alveolar air to a tissue cell. Use this pathway to explain two limits of inferring oxygen adequacy from pump output alone.

Stretch route | Design the next comparison

Optional extension uses the same model; no Higher-only endocrine mechanism is required.

T1. A pump C has 120 beats/min and 35 mL/beat. Compare its output with A and B. What does this show about using heart rate alone?T2. Design an area-only comparison with X, using an area of 9. State the concentration difference, thickness and predicted relative index.T3. The supplied model omits oxygen content and tissue demand. Explain how either could change the adequacy judgement even if output stayed the same.T4. Write a concise advice note to the model’s designer: one supported conclusion, one unsupported claim and one specific extra measurement.

Exit and reflection | Evidence before certainty

Answer independently or explain to an adult who records your reasoning.

E1. Calculate 80 beats/min × 50 mL/beat in L/min.E2. Why is X/Y not an area-only test?E3. Name one missing quantity needed to judge whether oxygen supply meets tissue demand.L1. Record the audience’s evidence question and the revision it prompted.

My next step Keep calculation units consistent. Choose a controlled comparison. Separate signal from material. State what evidence cannot establish.