1 - Getting Started ~5 mins
Put one hand gently on your chest and the other on your tummy. Breathe in slowly, then out. What moves? Today we will build a model that shows how air gets into our lungs, and then count how breathing changes when we move.
Keep this light: one curiosity beat only. Do not hand out bottles yet. Ask two or three pupils what they felt. Common answer: the chest rises. Some will feel the tummy move too; that is useful later when you name the diaphragm.
Link forward: tell the class that the heart speeds up when we move (from earlier work) and ask whether breathing might change too.
2 - How Our Lungs Work ~7 mins
Every breath you just took used a muscle you rarely notice. Watch this finished bottle model. Inside is a balloon like a lung. Across the base is a stretchy sheet like that muscle under your lungs.
What do you think happens to the balloon when I pull the base sheet? Watch as I pull gently, then push the sheet gently back up.
Your lungs are the soft, spongy parts in your chest that fill and empty with air. Under them is a sheet of muscle called the diaphragm (say: DY-uh-fram). When the diaphragm pulls down, space in the chest gets bigger and air goes in.
| Concept | Why it matters | Example |
|---|---|---|
| Lungs — soft, spongy organs in the chest that fill with air when we breathe in and empty when we breathe out | Every cell in the body needs something from the air the lungs take in, so healthy lungs help us run, play and think | After a long run on the yard your lungs work harder and you feel out of breath for a short time |
| Diaphragm — a sheet of muscle under the lungs that pulls down to let air in and relaxes back up so air can leave | Without the diaphragm moving, air would not move in and out of the lungs on its own | In our bottle model, the balloon sheet stretched over the base is the diaphragm; pull it and the lung balloon fills |
| Breathing rate — how many times you breathe in and out in a set time (introduce fully in the count step) | When the body works harder it needs more air, so breathing speeds up to match | Counting breaths for 30 seconds at rest, then after star jumps, shows the change clearly |
Order on the board: open with the amazement line, show the finished bottle, run the live pull and push first, then name lungs and diaphragm briefly. Do not stack long definitions before the demo.
Required demo (do this on the IWB table before pairs build): Hold up one finished bottle. Worked cycle to say aloud: I wonder what happens when I pull the base sheet. I predict the lung balloon will get bigger. I pull gently — look, the lung fills. I push the base back up — the lung empties. I think: when the diaphragm pulls down, space gets bigger so air goes in; when it relaxes and moves back up, air leaves.
Model vs body language: On the bottle we actively push the base up. In quiet real breathing, the diaphragm mostly relaxes and domes upward rather than forcefully pushing; keep that distinction if a pupil asks.
Misconception to head off: children often think lungs suck air in by themselves. Air is pushed in by outside pressure when the chest space gets bigger; the diaphragm makes that space.
Nature of STEM: Careful models and observations help us understand how the diaphragm pulls to make space for air to enter the lungs, and how it moves back up so air can leave.
Save breathing rate as a named term until the count investigation; here the two load-bearing ideas are lungs and diaphragm.
3 - Build a Lung in a Bottle ~12 mins
In pairs, finish your lung model. Most pairs get a kit with the lung balloon already fixed in the lid. Follow these three steps, then wait for the seal check. Do not free-test the pull on your own.
- Check the lung balloon hangs inside the bottle from the prepared lid.
- Stretch the base sheet tightly over the open bottom and tape all around so it is sealed.
- Hands up when your base looks sealed. Wait for my quick seal check, then hands off until the class signal in the next step.
Before the lesson (adult only)
- Remove the base of each bottle (scissors or craft knife; not a pupil job).
- Prepare each lid airway: make a hole in the bottle lid and fix the lung balloon (or a short straw with the balloon sealed over it) so the balloon hangs inside and the lid seal is airtight. This step is adult prep, not a pair task.
- Default kit: half-built. Lung already fixed in the lid for most pairs. Only confident pairs assemble the lung-in-lid from scratch if time and skill allow.
- Keep one finished demo bottle ready at all times so observation never depends on every pair seal working.
- Print nothing extra beyond Investigation Journal pages: bottles, balloons, tape and optional straws are the kit.
Build focus for pairs
- Confirm the pre-fixed lung hangs inside from the lid.
- Stretch the second balloon (cut open) or rubber sheet tightly over the open base and tape the edge sealed.
- Teacher-controlled seal check inside this build window: circulate and do a gentle test pull yourself (or watch the seal as the pair holds the bottle still). Retape weak edges or swap to a spare pre-built lid/kit. No free pair testing yet; the teaching pull stays for the next step.
- Stop. First whole-class observation pull is on the class signal in the next step.
If a seal looks weak: retape the base edge. A pin-hole in the lid seal also spoils the pull; swap to a spare pre-built lid if needed.
Overrun path (protect the two cores): At about the 10-minute mark, any pair still untaped or with a failed seal joins the demo bottle for the next step. Do not burn the observation or the breath-count journal chasing perfect seals. One successful model observation for every child matters more than every pair finishing a working kit. If build still overruns, shorten chatty extensions later, not the watch step or the journal counts.
Differentiation: less confident pairs keep the half-built default and only seal the base. Confident pairs may try a second, tighter base seal and compare later. Anyone stuck joins the demo bottle for the next step.
Safety: each pair keeps its own balloon; no sharing mouthpieces or straws. Adult-only bottle cutting and lid prep.
4 - Watch the Model Breathe ~7 mins
On the class signal, pull the diaphragm sheet gently downward. What happens to the lung balloon? Now push the sheet gently back up. What happens now?
In the model we push the sheet up. In your body the diaphragm mostly relaxes and moves back up on its own. Be ready to tell the class one thing you noticed.
This is whole-class oral observation, not a journal diagram step. Drive it after pairs have had the seal check. Fold watchers and demo-bottle pairs in with questions: Are they pulling slowly enough? What do you predict will happen on the push?
Look-fors: pupils link pull-down with fill and push-up with empty. Revoice for the body: the diaphragm pulls down to make space so air can go in; it relaxes and moves back up so air can leave. On the model we push the base up to show that move — say the pupil-facing bridge aloud so nobody thinks their own diaphragm is shoved upward like the balloon sheet.
If some models still fail: gather those pairs at the demo bottle and complete the observation there so nobody misses the idea.
5 - Count Breaths at Rest and After Moving ~14 mins
Your breathing rate is how many breaths you take in a set time. We will compare it at rest and after moving. One breath means one breathe-in and one breathe-out counted together. Air has a gas called oxygen that your muscles use when you run and play.
We will do one job at a time. Wait for my start and stop each time.
First: write your prediction on your Investigation Journal page. Use this stem: I think my breaths will ___ because ___.
Next: sit still. When I say start, count how many breaths you take in 30 seconds. Write that number when I say stop.
Then: do gentle star jumps for one minute (or march on the spot). I will time you.
After that: sit. When I say start, count breaths for 30 seconds again and write the new number when I say stop.
Last: look at both numbers. Did your breathing speed up?
Setup
Use the classroom clock or a simple stopwatch call-outs: you say start and stop for both 30-second counts and for the one-minute move. Reveal only the current beat on the board (prediction, then rest count, then move, then second count, then compare) so pupils do not skip ahead to star jumps. Pupils who should not do star jumps are timekeepers or count a partner's breaths instead.
Name the term here
Introduce breathing rate now (how many breaths in a set time). Link it to the two numbers they will write.
Shared counting rule (before the first timed count)
Agree on the IWB and say aloud: one breath = one in and one out together. Practise two or three slow breaths as a class so mixed in-only counting does not blur the rest-versus-after numbers.
Prediction stem
Have pupils write: I think my breaths will ___ because ___. Cue a simple because-clause (for example, because my body will need more air) so the later explain step has something to build on.
Full investigation cycle to model once before groups go
I wonder: does breathing change after we move? I predict: I will take more breaths after star jumps because my muscles will work harder and need more from the air. I test: count 30 seconds at rest, move for one minute, count 30 seconds again. I observed: rest was about 8 to 12 breaths; after moving it was higher. I think: when muscles work harder they use more of what is in the air, so breathing speeds up to match.
Fairness note (light touch): same counting time (30 seconds), same breath rule, and same kind of move for everyone who is moving. This is not a full fair-test lesson; keep the focus on compare before and after.
Safety: stop anyone who feels dizzy or light-headed; they sit and become a counter. No holding breath contests. Clear space for star jumps.
What healthy lungs need (brief science-talk): moving, fresh air, and not breathing smoke. Keep it practical and hopeful, not frightening.
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