• Quick retrieval from earlier learning (Pitch and loudness; Parts of a wave). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. How can you make a guitar string play a higher note? (make it looser / pluck it more softly / make it tighter or shorter / make it longer) → make it tighter or shorterPrompt: Shorter, tighter strings vibrate faster.
2. Pitch and loudness: which statement is true? (Hitting a drum harder makes a higher note. / Sounds get quieter the further you are from the source. / Longer strings make higher notes. / Loud sounds always have a high pitch.) → Sounds get quieter the further you are from the source.Prompt: Pitch is about how fast; loudness is about how big.
3. Which drum makes the lowest sound? (a drum with a very tight skin / a big drum with a loose skin / a small drum with a tight skin / a tiny drum) → a big drum with a loose skinPrompt: Big, loose skins vibrate slowly.

• Ask the class to make a wave with a rope or slinky and describe what moves and what doesn't.
• Share the objective: Frequency and amplitude of sound waves. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A guitar string vibrates 400 times in 4 seconds. What is the frequency of the sound, in hertz (Hz)?
• Step 1: 400 ÷ 4 = 100
• Step 2: So the answer is: 100 Hz
• Answer: 100 Hz
• 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. A guitar string vibrates 250 times in 5 seconds. What is the frequency of the sound, in hertz (Hz)? → 50 HzPrompt: Frequency is the number of waves (vibrations) per second.
2. A dog whistle produces sound at 25 kHz. What is this frequency in Hz? (1 kHz = 1000 Hz) → 25000 HzPrompt: “kilo” means one thousand.

• 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. Humans can hear from about 20 Hz to 20 000 Hz. Could a young person hear a sound of 25 kHz? (yes / no, it is ultrasound) → no, it is ultrasoundPrompt: Convert kHz to Hz first.
2. Two sound waves are shown on an oscilloscope. Wave B has taller peaks than wave A but the same spacing. How does B sound? (quieter / lower pitched / louder, with the same pitch / higher pitched) → louder, with the same pitchPrompt: Taller waves have a larger amplitude.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-6.