Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: Know what is meant by background radiation
Learning Objective/s:
  • Describe what background radiation is and identify its natural and man‑made sources.
  • Explain why measuring background radiation is essential for accurate experimental results and safety.
  • Calculate an average background count rate from repeated measurements and convert it to dose rate.
  • Evaluate methods to reduce background radiation effects in a laboratory setting.
Materials Needed:
  • Geiger‑Müller tube or scintillation counter
  • Lead bricks or other shielding material
  • Stopwatch or timer
  • Data recording worksheet
  • Projector for diagrams
  • Calculator
 Introduction:
Begin with a striking fact: even in a room with no visible sources, ionising radiation is constantly present. Review students’ prior knowledge of radiation detectors and dose units. Explain that today’s success criteria are to define background radiation, measure it, and discuss how to minimise its impact on experiments.
Lesson Structure:
  1. Do‑now (5’) – Quick quiz on types of radiation and safety symbols.
  2. Mini‑lecture (10’) – Define background radiation, show natural/man‑made sources and typical dose rates using the projector.
  3. Demonstration (10’) – Set up the detector, record background counts for 60 s, repeat three times.
  4. Data analysis activity (10’) – Students calculate the average count rate and convert to µSv h⁻¹ using a calibration factor.
  5. Discussion (8’) – Why background must be subtracted; effect of shielding and environment.
  6. Extension (7’) – Groups propose ways to reduce background in a lab and present brief rationales.
Conclusion:
Summarise that background radiation is ever‑present and must be measured and subtracted for accurate results. Ask students to complete an exit ticket stating one method to reduce background effects. Assign homework to research a real‑world example where background radiation monitoring is critical, such as in hospitals or nuclear power plants.