• Quick retrieval from earlier learning (Sound comes from vibrations; Speed = distance ÷ time). 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 / light from the string / the wood breathing / the string vibrating) → the string vibratingPrompt: Touch the string gently after plucking it.
2. A cyclist travels 50 m in 10 s. What is the average speed, in m/s? → 5 m/sPrompt: speed = distance ÷ time
3. Sound: which statement is true? (Sound travels through space between planets. / Sounds get fainter as you move further from the source. / Sound cannot travel through water. / Loud sounds do not involve vibrations.) → Sounds get fainter as you move further from the source.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: Speed of sound and echoes. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: You see lightning and hear the thunder 2 seconds later. Sound travels at about 340 m/s. About how far away is the storm, in metres?
• Step 1: 340 × 2 = 680
• Step 2: So the answer is: 680 m
• Answer: 680 m
• 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. You see lightning and hear the thunder 2 seconds later. Sound travels at about 340 m/s. About how far away is the storm, in metres? → 680 mPrompt: Light arrives almost instantly; the delay is the sound travelling.
2. You shout towards a cliff and hear the echo 2 s later. Sound travels at 340 m/s. How far away is the cliff, in metres? → 340 mPrompt: The sound goes to the cliff and back.

• 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 6 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. You shout towards a cliff and hear the echo 1 s later. Sound travels at 340 m/s. How far away is the cliff, in metres? → 170 mPrompt: The sound goes to the cliff and back.
2. You see lightning and hear the thunder 2 seconds later. Sound travels at about 340 m/s. About how far away is the storm, in metres? → 680 mPrompt: Light arrives almost instantly; the delay is the sound travelling.

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