| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that α-particles have discrete energies but that β-particles have a continuous range of energies because (anti)neutrinos are emitted in β-decay |
Learning Objective/s:
- Describe why α‑particles exhibit discrete kinetic energies.
- Explain how three‑body β‑decay produces a continuous electron energy spectrum.
- Compare the energy spectra and detection signatures of α‑ and β‑decay.
- Apply conservation of energy and momentum to calculate Q‑values for α‑ and β‑decay.
- Evaluate the role of the (anti)neutrino in preserving energy conservation in β‑decay.
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Materials Needed:
- Projector and screen
- Printed handouts with decay equations and sample spectra
- Spectrometer simulation software (e.g., PhET)
- Clicker/response system for quick checks
- Worksheet with comparison table
- Calculators
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Introduction:
Begin with a striking image of radiation detectors showing sharp α peaks and smooth β backgrounds to capture interest. Review students’ prior knowledge of nuclear decay and the concept of Q‑value. State that by the end of the lesson they will be able to explain why these two types of radiation differ in their energy spectra and how the neutrino resolves the β‑decay puzzle.
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Lesson Structure:
- Do‑now (5') – Quick quiz on identifying α‑ and β‑particles and recalling Q‑value definition.
- Mini‑lecture (10') – Two‑body kinematics of α‑decay and why the α‑particle energy is discrete.
- Simulation demo (8') – Use software to display a line spectrum for α‑decay.
- Mini‑lecture (10') – Three‑body β‑decay, energy sharing with the (anti)neutrino, and the resulting continuous spectrum.
- Interactive activity (12') – In pairs, students plot a simulated β‑spectrum and annotate regions corresponding to different neutrino energy shares.
- Comparison discussion (8') – Complete the provided comparison table, highlighting key differences.
- Formative check (5') – Clicker questions targeting the learning objectives.
- Summary & exit ticket (5') – Students write one sentence explaining why β‑decay yields a continuous spectrum; collect for assessment.
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Conclusion:
Recap the contrasting energy distributions of α‑ and β‑decay and the essential role of the (anti)neutrino in conserving energy. Collect the exit‑ticket sentences as a rapid retrieval check. For homework, assign textbook problems calculating Q‑values and interpreting sample spectra.
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