• 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. Water is poured into identical glass bottles to different levels. You blow across the tops. Which bottle gives the highest note? (the one with the least water / they are all the same / the one with the most water (shortest air column) / the empty one) → the one with the most water (shortest air column)Prompt: When you blow, the air inside vibrates.
2. Pitch and loudness: which statement is true? (Longer strings make higher notes. / Hitting a drum harder makes a higher note. / Loud sounds always have a high pitch. / Sounds get quieter the further you are from the source.) → Sounds get quieter the further you are from the source.Prompt: Pitch is about how fast; loudness is about how big.
3. How can you make a guitar string play a higher note? (make it tighter or shorter / make it longer / make it looser / pluck it more softly) → make it tighter or shorterPrompt: Shorter, tighter strings vibrate faster.

• 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 5 seconds. What is the frequency of the sound, in hertz (Hz)? → 200 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 15 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 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. A guitar string vibrates 125 times in 0.5 seconds. What is the frequency of the sound, in hertz (Hz)? → 250 HzPrompt: Frequency is the number of waves (vibrations) per second.
2. Why can bats hear sounds that people cannot? (Sound travels faster for bats / Bats hear only low frequencies / Their hearing range extends to much higher frequencies / They have bigger amplitude ears) → 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.