Science lesson plan · 8th grade (Year 9 in England) · 45 minutes
Transverse and longitudinal waves
Light, sound and waves
CCSS NGSS.MS-PS4-1CCSS NGSS.HS-PS4-1England: KS3 Physics: WavesEngland: GCSE Combined Science: Waves
Objective and success criteria
Students will: Transverse and longitudinal waves.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Parts of a wave; How sound travels through solids, liquids and gases
Leads to: Seismic waves as evidence for Earth's layers
Materials: Slinky or rope, Mirrors and torches, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Parts of a wave; How sound travels through solids, liquids and gases). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Why does sound travel faster in steel than in air? (Sound is magnetic / Steel is shiny / Particles in solids are close together and strongly linked, so vibrations pass on quickly / Air has no particles) → Particles in solids are close together and strongly linked, so vibrations pass on quicklyPrompt: Think about how close particles are.
- 20 waves pass a point in 5 seconds. What is the frequency, in hertz (Hz)? → 4 HzPrompt: Frequency is the number of waves per second.
- In which direction do air particles vibrate when a sound wave passes? (they do not move / backwards and forwards, parallel to the direction the sound travels / up and down, at right angles to the wave / in circles) → backwards and forwards, parallel to the direction the sound travelsPrompt: Sound is a longitudinal wave.
Hook · 5 min
- Ask the class to make a wave with a rope or slinky and describe what moves and what doesn't.
- Share the objective: Transverse and longitudinal waves. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Is this a transverse or a longitudinal wave: seismic P waves?
- Step 1: In longitudinal waves, vibrations are parallel to the direction the wave travels.
- Step 2: So the answer is: longitudinal
- Answer: longitudinal
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Is this a transverse or a longitudinal wave: sound? (transverse / longitudinal) → longitudinalPrompt: Compare the direction of vibration with the direction the wave travels.
- What are compressions and rarefactions? (regions where particles are squashed together and spread apart in a longitudinal wave / the start and end of a wave / two kinds of light / the peaks and troughs of a transverse wave) → regions where particles are squashed together and spread apart in a longitudinal wavePrompt: Think of a slinky being pushed.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Types of wave: which statement is NOT true? (Waves transfer energy without transferring matter. / Sound waves are longitudinal. / Water particles travel across the ocean with the waves. / All electromagnetic waves are transverse.) → Water particles travel across the ocean with the waves.Prompt: Which kind of wave is light?
- Is this a transverse or a longitudinal wave: ultrasound? (transverse / longitudinal) → longitudinalPrompt: Compare the direction of vibration with the direction the wave travels.
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Parts of a wave.
- Use concrete materials: slinky or rope.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Seismic waves as evidence for Earth's layers.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-8.
Free lesson plan from eurekami.com/lesson-plan-builder