• Quick retrieval from earlier learning (Sound comes from vibrations; The particle model). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. What makes the sound when you pluck a guitar string? (the string getting hot / the wood breathing / the string vibrating / light from the string) → the string vibratingPrompt: Touch the string gently after plucking it.
2. Which state is described: particles touching but able to slide past each other? (solid / liquid / gas) → liquidPrompt: How close are the particles, and how do they move?
3. Sound: which statement is true? (Loud sounds do not involve vibrations. / Sound travels through space between planets. / Sound cannot travel through water. / Sound can travel through solids, liquids and gases.) → Sound can travel through solids, liquids and gases.Prompt: Can sound travel where there is nothing at all?

• Ask the class to make a wave with a rope or slinky and describe what moves and what doesn't.
• Share the objective: How sound travels through solids, liquids and gases. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Why does sound travel faster in steel than in air?
• Step 1: Sound travels at about 340 m/s in air, 1500 m/s in water and over 5000 m/s in steel.
• Step 2: So the answer is: Particles in solids are close together and strongly linked, so vibrations pass on quickly
• Answer: Particles in solids are close together and strongly linked, so vibrations pass on quickly
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. In which direction do air particles vibrate when a sound wave passes? (in circles / they do not move / backwards and forwards, parallel to the direction the sound travels / up and down, at right angles to the wave) → backwards and forwards, parallel to the direction the sound travelsPrompt: Sound is a longitudinal wave.
2. Sound travels at about 1500 m/s in water. How far does it travel in 5 s, in m? → 7500 mPrompt: distance = speed × time

• 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.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Why does sound travel faster in steel than in air? (Steel is shiny / Sound is magnetic / Air has no particles / Particles in solids are close together and strongly linked, so vibrations pass on quickly) → Particles in solids are close together and strongly linked, so vibrations pass on quicklyPrompt: Think about how close particles are.
2. How sound travels: which statement is NOT true? (Whales can communicate over long distances underwater. / Sound waves are longitudinal. / In a sound wave, air particles travel all the way from the source to your ear. / Sound travels faster in water than in air.) → In a sound wave, air particles travel all the way from the source to your ear.Prompt: Why do we see lightning before we hear thunder?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.