• 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? (pluck it more softly / make it longer / make it looser / make it tighter or shorter) → 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. / Loud sounds always have a high pitch. / Pitch is how high or low a sound is. / Longer strings make higher notes.) → Pitch is how high or low a sound is.Prompt: Pitch is about how fast; loudness is about how big.
3. How do you make a drum sound louder? (hit it more gently / cover it with a cloth / use a smaller drum / hit it harder) → hit it harderPrompt: Bigger vibrations make louder sounds.

• 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 200 times in 2 seconds. What is the frequency of the sound, in hertz (Hz)? → 100 HzPrompt: Frequency is the number of waves (vibrations) per second.
2. Humans can hear from about 20 Hz to 20 000 Hz. Could a young person hear a sound of 5 kHz? (yes / no, it is ultrasound) → yesPrompt: Convert kHz to Hz first.

• 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. Humans can hear from about 20 Hz to 20 000 Hz. Could a young person hear a sound of 5 kHz? (yes / no, it is ultrasound) → yesPrompt: Convert kHz to Hz first.
2. Why does the upper limit of hearing often fall as people get older? (Sound gets slower / The ear canal gets wider / Sensitive cells in the inner ear are gradually damaged / Older people make higher sounds) → Sensitive cells in the inner ear are gradually damagedPrompt: Loud noise speeds this up.

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