Lesson Plan

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Lesson Plan
Grade: 9 Date: 18/01/2026
Subject: Physics
Lesson Topic: Know that the speed of sound in air is approximately 330-350 m/s
Learning Objective/s:
  • Describe the relationship between temperature and the speed of sound in air.
  • Explain why the speed of sound differs between gases, liquids, and solids.
  • Calculate the speed of sound using measured distance and time interval.
  • Identify common sources of error in experimental determination of sound speed.
  • Compare typical sound speeds in different media.
Materials Needed:
  • Two microphones or sound sensors
  • Measuring tape or ruler (≈ 2 m)
  • Oscilloscope or digital timer with data‑logging capability
  • Computer with spreadsheet software
  • Thermometer
  • Worksheet with calculation tasks
  • Projector for diagram presentation
 Introduction:
Begin with a short video of a thunderclap and ask students how quickly the sound arrived compared to the flash. Recall that sound travels as a wave and that its speed depends on the medium and temperature. Today they will determine the speed of sound in air and be able to predict its value within the 330‑350 m s⁻¹ range.
Lesson Structure:
  1. Do‑now (5'): Quick quiz on wave‑speed concepts (check for understanding).
  2. Mini‑lecture (10'): Theory of sound speed, temperature relation, and media differences (check).
  3. Demonstration (15'): Set up two microphones 2 m apart, produce a clap, record Δt on the oscilloscope (check).
  4. Group activity (15'): Repeat measurements, calculate v, average results, complete worksheet (check).
  5. Error‑analysis discussion (10'): Identify sources of error and suggest improvements (check).
  6. Summary quiz (5'): Exit ticket with one calculation and one conceptual question (check).
Conclusion:
Review the key factors that influence the speed of sound and confirm that measured values fall within the expected 330‑350 m s⁻¹ range. Students complete an exit ticket summarising one source of error and its mitigation. For homework, assign a problem set calculating sound speed in water and steel using the given formulas.