| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Know the sources that make a significant contribution to background radiation including: (a) radon gas (in the air) (b) rocks and buildings (c) food and drink (d) cosmic rays |
Learning Objective/s:
- Describe the four main natural sources of background radiation and their typical dose contributions.
- Explain why radon gas is the largest contributor and how building characteristics affect its levels.
- Compare the influence of altitude and building materials on radiation exposure.
- Calculate approximate annual doses from each source using the provided data.
- Evaluate simple strategies to reduce personal exposure to background radiation.
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Materials Needed:
- Projector and screen
- PowerPoint/Google Slides presentation
- Handout with summary table of typical annual doses
- Radon‑detector demonstration video or kit
- Sample granite rock (or photo) for discussion
- Bananas (for “banana equivalent dose” activity)
- Worksheet for calculations and exit ticket
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Introduction:
Did you know the air in this classroom contains invisible ionising radiation? You already know that radiation can be harmful, so today we’ll explore where the natural background dose comes from. By the end of the lesson you will be able to identify the main sources, explain their relative importance, and suggest ways to minimise exposure.
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Lesson Structure:
- Do‑now (5'): Quick quiz on basic radiation concepts.
- Mini‑lecture (10'): Overview of background radiation and the four natural sources with slides.
- Data‑analysis activity (15'): In groups, use the handout table to calculate each source’s percentage of the total dose and discuss why radon dominates.
- Demonstration/video (5'): Show a radon‑detector reading in a basement and discuss ventilation.
- Hands‑on exploration (10'): Examine a granite sample (or image) and relate its radionuclide content to indoor gamma exposure.
- Quick‑fire Q&A (5'): Review key exam points from the source notes.
- Exit ticket (5'): Write one practical measure to reduce exposure to any of the sources.
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Conclusion:
We have revisited the four natural contributors to background radiation, highlighted radon as the biggest source, and examined how altitude and building materials affect dose. Complete the exit ticket, then for homework research the average radon level in your local area and write a short paragraph on any mitigation steps that could be taken.
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