• 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. Which drum makes the lowest sound? (a tiny drum / a big drum with a loose skin / a drum with a very tight skin / a small drum with a tight skin) → a big drum with a loose skinPrompt: Big, loose skins vibrate slowly.
2. Pitch and loudness: which statement is true? (Loud sounds always have a high pitch. / Longer strings make higher notes. / Faster vibrations make higher-pitched sounds. / Hitting a drum harder makes a higher note.) → Faster vibrations make higher-pitched sounds.Prompt: Pitch is about how fast; loudness is about how big.
3. Water is poured into identical glass bottles to different levels. You blow across the tops. Which bottle gives the highest note? (the empty one / they are all the same / the one with the least water / the one with the most water (shortest air column)) → the one with the most water (shortest air column)Prompt: When you blow, the air inside vibrates.

• 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 1000 times in 4 seconds. What is the frequency of the sound, in hertz (Hz)? → 250 HzPrompt: Frequency is the number of waves (vibrations) per second.
2. A dog whistle produces sound at 5 kHz. What is this frequency in Hz? (1 kHz = 1000 Hz) → 5000 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 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 15 kHz? (yes / no, it is ultrasound) → yesPrompt: Convert kHz to Hz first.
2. Why can bats hear sounds that people cannot? (Bats hear only low frequencies / Their hearing range extends to much higher frequencies / They have bigger amplitude ears / Sound travels faster for bats) → Their hearing range extends to much higher frequenciesPrompt: Bats use ultrasound to find insects.

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