| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Explain safety precautions for all ionising radiation in terms of reducing exposure time, increasing distance between source and living tissue and using shielding to absorb radiation |
Learning Objective/s:
- Describe the three fundamental principles (time, distance, shielding) for reducing ionising radiation exposure.
- Explain how each principle reduces dose, including the inverse‑square law and material attenuation.
- Apply appropriate safety measures to a laboratory scenario by selecting suitable shielding and calculating safe distances.
- Demonstrate correct use of PPE and a radiation survey meter during experimental work.
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Materials Needed:
- Projector and slide deck
- Worksheet / safety‑plan template
- Mock radiation source (sealed or simulated)
- Lead blocks, acrylic sheets, and polyethylene slabs for shielding demos
- Remote‑handling tools (tongs or manipulators)
- Radiation survey meter
- Lab coats, gloves, and eye protection
- Safety signage and distance markers
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Introduction:
Begin with a quick question: “What would happen if you stood directly next to an active radiation source for several minutes?” Students recall previous work on radiation types and hazards. Explain that today they will learn three concrete ways to keep dose low and will be able to plan a safe experiment by the end of the lesson.
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Lesson Structure:
- Do‑now (5') – short quiz on ionising radiation types and associated risks.
- Mini‑lecture (10') – introduce the three safety principles with diagrams and real‑world examples.
- Demonstration (10') – use a point source and a ruler to show the inverse‑square law and how distance reduces intensity.
- Group activity (15') – students design a safety plan for a given lab experiment, selecting shielding materials and calculating a safe working distance.
- Practical check (10') – students practise using the survey meter, record dose‑rate readings, and don PPE correctly.
- Plenary (5') – recap key points, answer lingering questions, and highlight common mistakes.
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Conclusion:
Summarise how reducing time, increasing distance, and using appropriate shielding together minimise radiation dose. Ask each pair to write one “exit ticket” sentence stating which principle they consider most critical for their designed experiment. For homework, students complete a worksheet that requires them to choose shielding for a mixed‑radiation scenario and justify their choices.
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