Lesson Plan

• Describe what an echo is and how it results from the reflection of sound waves.
• Explain the conditions required for an echo to be heard, including the 0.1 s time gap and surface characteristics.
• Calculate the distance to a reflecting surface using the measured echo time and the speed of sound.
• Analyse factors that affect echo intensity such as surface material, size, angle of incidence, and atmospheric conditions.

• Projector and screen
• Whiteboard and markers
• Ray‑diagram handout
• Stopwatch or timer app
• Measuring tape or ruler
• Worksheet with practice questions
• Calculator

Show a short video of a canyon echo to spark curiosity. Ask students what they already know about how sound travels and what happens when a sound returns. State that by the end of the lesson they will be able to describe an echo, list the conditions needed to hear one, and calculate distances using echo timing.

1. Do‑now (5 min): Students write a quick definition of an echo and share; teacher notes common misconceptions.
2. Mini‑lecture & diagram (10 min): Explain sound‑wave reflection, present the 0.1 s rule, and display a ray diagram on the projector.
3. Demonstration (8 min): Use a speaker and a large board; measure the round‑trip time with a stopwatch and calculate the distance together.
4. Group activity (12 min): Students complete a worksheet calculating distances for given times and discuss factors influencing echo intensity.
5. Concept check (5 min): Quick quiz (e.g., Kahoot) on conditions for an echo and the difference between echo and reverberation.
6. Summary & exit ticket (5 min): Recap key points; students write one thing they learned and one lingering question on a sticky note.

Review the definition of an echo, the minimum distance requirement, and how to use the formula d = vt⁄2. Collect exit tickets and assign homework: students find an everyday example of an echo, photograph or sketch it, and explain why the conditions for an echo are met.