Lesson Plan

• Describe the spontaneous nature of radioactive decay and why external conditions do not affect it.
• Explain the random (statistical) character of decay and interpret the decay constant.
• Apply the exponential decay law to calculate remaining nuclei and half‑life.
• Distinguish between the main types of radioactive decay and their emitted particles.

• Projector and slide deck
• Printed worksheet with decay problems
• Scientific calculators
• Online decay simulation (e.g., PhET)
• Whiteboard and markers

Begin with a quick poll: “If you could heat a radioactive sample, would it decay faster?” Use this to surface common misconceptions. Review students’ prior knowledge of half‑life and exponential decay. State that by the end of the lesson they will be able to explain why decay is both spontaneous and random and use the decay constant in calculations.

1. Do‑now (5') – students answer two misconception statements on sticky notes.
2. Mini‑lecture (10') – slides covering spontaneous vs. random nature, decay constant, and Poisson statistics.
3. Guided example (10') – calculate half‑life from a given decay constant and predict remaining nuclei after several half‑lives.
4. Simulation activity (10') – use an online decay simulator to observe random decay events and compare with the smooth exponential curve.
5. Group data‑interpretation task (10') – each group plots simulated data, identifies half‑life, and discusses randomness.
6. Check for understanding (5') – exit ticket: one sentence explaining why temperature does not affect nuclear decay.

Recap that radioactive decay occurs without external triggers and that individual decay events are unpredictable, though large‑scale behaviour follows simple statistical laws. Collect exit tickets to gauge understanding of spontaneity and randomness. For homework, assign the worksheet that reinforces half‑life calculations and asks students to design a simple experiment to test the randomness of decay.