mechanics of breathing
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.
Lesson Overview
Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA
Learning Objectives
- Explain the key ideas of mechanics of breathing
- Apply mechanics of breathing to exam-style questions
- Develop independent study skills
- Build cross-topic connections
Prerequisites
- Read the revision notes for mechanics of breathing first (GCSE Revise summary)
- Key vocab to pre-teach: Key Principle, Inspiration is an ACTIVE process
- Basic skills: reading the summary notes and answering the practice questions there
Materials & Equipment
- Exercise book, coloured pens
- Ruler
- Printed revision notes (link below)
- Internet for videos (see Resources)
Lesson 1: Introduction: mechanics of breathing
Duration: 50 minutes
Starter Activity (5 minutes)
Quick Recall
Write down everything you already know about mechanics of breathing. Then check against the key terms: Key Principle, Inspiration is an ACTIVE process. Use a mini-whiteboard or paper.
Main Content (35 minutes)
Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: Key Principle, Inspiration is an ACTIVE process.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Before lesson: Read the script below. Pre-teach key vocab: Key Principle, Inspiration is an ACTIVE process.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: mechanics of breathing. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Physical Education because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
Mins 0-5 - Hook: "Today: mechanics of breathing. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Physical Education because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look
Start with the revision notes summary, then attempt: Describe the role of the diaphragm during inspiration.
Plenary (5 minutes)
Check Out
Your student states one thing they learned and one question they still have about mechanics of breathing.
Lesson 2: Core Concepts: mechanics of breathing
Duration: 50 minutes
Starter Activity (5 minutes)
Review Previous Lesson
Quick recap: write 3 key points from Lesson 1 on mechanics of breathing. Check them against the notes below.
Main Content (35 minutes)
Key Principle: Breathing (ventilation) works on the basis of pressure differences . Air always moves from an area of high pressure to an area of low pressure. By changing the volume of the thorax (chest cavity), the body changes the pressure inside the lungs, causing air to move in or out.
Inspiration is an ACTIVE process: - it requires muscle contraction.
Quiet expiration at rest is a PASSIVE process: - it does not require muscle contraction. It relies on the elastic recoil of the lungs and the relaxation of the inspiratory muscles.
Forced expiration during exercise is an ACTIVE process.: The internal intercostal muscles contract to pull the ribs down and in more forcefully. The abdominal muscles also contract, pushing the diaphragm up and compressing the lungs to expel air more quickly.
During exercise, both the rate and depth of breathing increase: to meet the higher demand for oxygen and to remove more carbon dioxide.
PE Exam Tips — Mechanics of Breathing: 1. For Mechanics of Breathing questions, use subject-specific terminology precisely 2. Support every point with specific evidence or examples 3. Show balanced analysis — consider different perspectives before reaching a conclusion 4. Link your understanding of Mechanics of Breathing to real-world contexts where possible 5. For longer answers, plan your response to address all parts of the question
| Term | Meaning | Example |
|---|---|---|
| Diaphragm | Contracts and flattens (moves down) | Increases thorax volume top-to-bottom |
| External intercostals | Contract, lifting ribs up and out | Increases thorax volume front-to-back and side-to-side |
| Internal intercostals | Relax | Allow ribs to move up and out |
| Process | Passive (elastic recoil) | Active (muscle contraction) |
| Diaphragm | Relaxes (returns to dome shape) | Pushed up by abdominal muscle contraction |
| External intercostals | Relax | Relax |
| Internal intercostals | Relax | Contract (pull ribs down and in) |
| Abdominal muscles | Not involved | Contract (compress abdomen, push diaphragm up) |
Practice (10 minutes)
Q: Describe the role of the diaphragm during inspiration.
Answer: During inspiration, the diaphragm contracts and moves downwards (flattens from its dome shape). This increases the volume of the thorax top-to-bottom, which decreases the pressure inside the lungs, causing air to rush in.
Plenary (5 minutes)
Explain Back
Your student teaches the key points back to you without looking. Fill any gaps immediately.
Lesson 3: Application: mechanics of breathing
Duration: 50 minutes
Starter Activity (5 minutes)
Quick Recall
Recall the key terms: Key Principle, Inspiration is an ACTIVE process. Define each in one sentence.
Main Content (35 minutes)
Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.
Q1: Describe the role of the diaphragm during inspiration.
Answer: During inspiration, the diaphragm contracts and moves downwards (flattens from its dome shape). This increases the volume of the thorax top-to-bottom, which decreases the pressure inside the lungs, causing air to rush in.
Q2: Explain why quiet expiration at rest is described as a passive process.
Answer: Quiet expiration at rest is passive because it does not require muscle contraction. The diaphragm and external intercostal muscles simply relax, and the elastic recoil of the lungs and the weight of the ribs moving downwards and inwards decreases the thorax volume, increasing pressure and forcing air out.
Q3: How does forced expiration during exercise differ from quiet expiration at rest?
Answer: Forced expiration during exercise is an active process involving the contraction of the internal intercostal muscles (pulling ribs down and in) and the abdominal muscles (pushing the diaphragm up). This expels air more quickly and forcefully than passive expiration at rest.
Q4: Explain how an increase in thorax volume causes air to enter the lungs.
Answer: When the thorax volume increases (due to diaphragm contracting down and ribs moving up and out), the pressure inside the lungs decreases below atmospheric pressure. Air moves from the higher atmospheric pressure outside into the lower pressure inside the lungs, down the pressure gradient.
Q5: How is breathing rate regulated during exercise?
Answer: Chemoreceptors in the aorta and carotid arteries detect rising CO₂ levels in the blood during exercise. They send signals to the medulla oblongata (respiratory centre), which sends nerve impulses to the diaphragm and intercostal muscles, increasing the rate and depth of breathing.
Q6: Calculate minute ventilation if tidal volume is 500 ml and breathing rate is 14 breaths/min.
Answer: Minute ventilation = tidal volume × breathing rate = 500 ml × 14 = 7,000 ml/min = 7.0 l/min.
Plenary (5 minutes)
Error Review
Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.
Lesson 4: Exam Practice: mechanics of breathing
Duration: 50 minutes
Starter Activity (5 minutes)
Command Words
Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).
Main Content (35 minutes)
Exam-Style Question
Attempt a past-paper style question on mechanics of breathing from the exam board past paper finder (see Resources), then mark it against the scheme.
Exam Tips: Always explain the full chain: muscle action → volume change → pressure change → air movement | Use "contracts" and "relaxes" - don't just say the diaphragm "goes down" | Remember: inspiration is always active; quiet expiration is passive; forced expiration is active | Pressure and volume have an inverse relationship - learn this principle | Be ready to explain how breathing changes during exercise (both rate AND depth increase) | Know the role of chemoreceptors and the medulla in regulating breathing
Common Errors: Watch Out! Students often think lactic acid causes doms. Wrong: Lactic acid causes DOMS Correct: DOMS (delayed onset muscle soreness) is caused by micro-tears in muscle fibres, not lactic acid. Lactic acid is cleared within an hour of exercise. Students often think veins always carry deoxygenated blood. Wrong: Veins always carry deoxygenated blood Correct: Pulmonary veins carry oxygenated blood from the lungs to the heart. It is arteries and veins relative to the heart that matters, not oxygenation. Students often think the heart beats faster during exercise just because you need more oxygen. Wrong: The heart beats faster during exercise just because you need more oxygen Correct: Heart rate
Stretch & Challenge (Grade 8-9):
- Synoptic links: explain how mechanics of breathing connects to another Physical Education topic you have studied
- Real-world: research one real-world use or example of mechanics of breathing
- Critical: "What are the limitations of the models used in mechanics of breathing?"
Plenary (5 minutes)
Assessment Criteria
- Got it: Confident explanation + correct worked examples
- Getting there: Main points OK, needs support with detail
- Not yet: Confused on key concepts - re-run Lesson 2
Homework & Consolidation
- Consolidation: Re-answer any Lesson 3 practice questions answered incorrectly (20 mins)
- Retrieval: Write flashcards for the key terms: Key Principle, Inspiration is an ACTIVE process (10 mins)
- Exam practice: One past-paper question on mechanics of breathing from the board websites (15 mins)
- Extension: Explain mechanics of breathing to someone else in your own words (10 mins)