Communication with Light & Sound · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Sending messages with light and sound

Science · Waves, Light & Sound · ages 6-7
Name ______________________   Date ____________

  1. Which of these could send a message using sound?

    • A mirror
    • A string telephone
    • A torch

  2. Which of these could send a message using light?

    • A flashing torch
    • A string telephone
    • A drum

  3. A loose, floppy string works as well as a tight string in a cup telephone.

    Circle one:   True   False

  4. Why can two friends use torch flashes to send an agreed message at night?

    • A torch makes its own light.
    • A torch needs sunlight to make a message.
    • A torch carries the message using sound.

  5. You speak into a cup telephone with a tight string. How does your message reach the other cup?

    • The string changes spoken words into flashes of light.
    • The words travel only through air; the string does nothing.
    • Vibrations travel through the cups and string.

  6. A torch flashes twice, pauses, then flashes twice more. How many flashes are in the whole signal?

    flashflashpauseflashflash

    Answer: ______________

  7. Ben uses a flash pattern for 'come here'. Asha thinks it means 'stay there'. What should they do before testing again?

    • Repeat the pattern with a brighter torch without discussing it.
    • Change to a longer string without discussing the flash pattern.
    • Agree on one meaning for that flash pattern.

  8. Mia wants to find out whether tight string helps her cup telephone. Which test lets her compare string tightness?

    • Use new cups and new messages whenever string tightness changes.
    • Use the same cups and message; change only string tightness.
    • Change the distance and voice whenever string tightness changes.
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Sending messages with light and sound W1-mt_ZL9qVVnpwN-s1

  1. A string telephone · A string telephone carries your voice, which is sound, along the string.
  2. A flashing torch · A torch makes light flashes that someone far away can see.
  3. False · A loose string usually carries speech poorly. Gently pull it tight and test the same message again.
  4. A torch makes its own light. · A switched-on torch makes light. Its flashes can reach a viewer even when there is no sunlight.
  5. Vibrations travel through the cups and string. · Speech makes the first cup vibrate. The string carries vibrations to the second cup, which makes sound.
  6. 4 · Count the flashes and skip the pause. Two flashes plus two more make four flashes.
  7. Agree on one meaning for that flash pattern. · Seeing a pattern is not enough to understand it. Both people need to agree on its meaning.
  8. Use the same cups and message; change only string tightness. · Change only string tightness. Keep the cups, message, distance and voice the same.
Worksheet · LightMySky