Lesson Plan

• Describe how particle vibration aligns with the direction of propagation in longitudinal waves.
• Identify compressions and rarefactions as the defining features of longitudinal waves.
• Explain why sound waves and seismic P‑waves are modeled as longitudinal waves.
• Apply the wave‑speed relationship v = fλ to longitudinal wave scenarios.

• Projector or interactive whiteboard
• Slinky or spring to demonstrate compressions and rarefactions
• Speaker or diaphragm model
• Printed diagram of longitudinal wave and comparison table
• Worksheet with concept questions and speed calculations
• Calculators

Begin with a short video of a slinky being compressed and released to capture interest. Ask students to recall how transverse waves move on a rope and link that to prior knowledge of wave energy transport. State that by the end of the lesson they will be able to describe particle motion in longitudinal waves and model sound and P‑waves accurately.

1. Do‑now (5 min): Quick quiz on wave types from the previous lesson.
2. Demonstration (10 min): Use a slinky to show compressions and rarefactions, labeling particle motion parallel to travel.
3. Direct instruction (10 min): Explain longitudinal‑wave characteristics, present the v = fλ formula and the speed‑of‑sound equation.
4. Guided practice (10 min): In pairs, identify compressions/rarefactions in diagrams and calculate wave speed for a sound‑wave example.
5. Concept check (5 min): Mini‑whiteboard responses to “Why are sound and P‑waves longitudinal?”
6. Summary & exit ticket (5 min): Students write one key idea and one lingering question on a sticky note.

Review the checklist items, emphasizing the link between particle motion and wave propagation. Collect exit tickets to gauge understanding, and assign a homework task to research another longitudinal wave (e.g., ultrasound) and calculate its speed using provided data.