Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: Describe the emission of radiation from a nucleus as spontaneous and random in direction
Learning Objective/s:
  • Describe why nuclear emission occurs spontaneously without external prompting.
  • Explain the random, isotropic direction of emitted particles and photons.
  • Compare the properties of alpha, beta, and gamma radiation (charge, mass, penetrating power, nuclear changes).
  • Interpret experimental evidence that demonstrates isotropic emission.
  • Apply appropriate shielding concepts for each type of radiation.
Materials Needed:
  • Projector or interactive whiteboard
  • PowerPoint slides with decay diagrams
  • Printed handouts of the emission comparison table
  • Spherical detector array simulation (software or physical model)
  • Geiger‑Müller counter demonstration kit
  • Shielding materials (paper, aluminium sheet, lead block)
  • Worksheet for practice problems
 Introduction:
Begin with a striking image of a glowing radioactive source and ask students how they think the radiation spreads. Recall prior learning on atomic structure and unstable nuclei. Explain that today they will investigate why decay occurs spontaneously and why emitted particles travel in random directions, with success measured by their ability to explain isotropy and differentiate radiation types.
Lesson Structure:
  1. Do‑now (5’) – Quick quiz on previous lesson about atomic nuclei and stability.
  2. Mini‑lecture (10’) – Explain spontaneity of decay and the exponential law using slides.
  3. Demonstration (10’) – Show Geiger‑Müller counters around a small source to illustrate isotropic counts.
  4. Interactive activity (15’) – Students use the spherical detector simulation to record counts and discuss randomness.
  5. Comparison task (10’) – In groups, fill a table comparing α, β, γ characteristics and nuclear changes.
  6. Check for understanding (5’) – Exit ticket: one sentence describing why emission is spontaneous and random.
Conclusion:
Summarise that nuclear decay is an inherent, spontaneous process producing radiation in all directions, and review the key differences among alpha, beta, and gamma emissions. Ask students to complete an exit ticket describing one safety implication of isotropic radiation. Assign homework to solve worksheet problems on decay equations and shielding calculations.