Communication with Light & Sound
Design and build a device that uses light or sound to solve the problem of communicating over a distance
What a learner can do afterwards
- Design a device that uses light or sound to communicate over a distance (e.g. string telephone, torch signals)
- Build and test the device, identifying what works and what could be improved
- Explain how the device uses properties of light or sound to transmit information
1 · Read
You have learned that torches make light and vibrating things can make sound. Use either to send a message across a distance. A torch uses flashes. A string telephone uses your voice. Before using flashes, both people must agree what each pattern means.
Ask an adult to make a small hole in the bottom of each paper cup. Thread string through the holes and tie knots inside. Two people gently pull the string tight. One speaks into a cup while the other listens. Speech makes the first cup vibrate. Vibrations travel along the string to the second cup.
Test your telephone with a short message. Ask your friend to repeat what they heard. A loose string usually carries speech poorly. Compare loose and tight string while keeping the cups, message, distance and voice the same. Changing only string tightness helps you find whether it made a difference.
A torch makes its own light, so its flashes can be seen at night. Keep a clear path to your friend. If flashes are hard to see, move closer and test again. Use a small battery torch below face level. Never use a laser. Count each flash once and skip the pauses.
Cup and string vibrations can carry speech. Torch flashes can carry an agreed message. Test whether your friend receives the message.
Reading and flashcards about checking light and sound messages, written for this dataset.
More to read
Check what your friend received
Choose a short word for your cup-telephone test. Say it into one cup and ask your friend to repeat what they heard. Swap jobs so both people can try speaking and listening.
If the word is hard to hear, test the string. Compare loose and tight string with the same cups, word, distance and voice. Changing only tightness helps you check its effect. An adult should make the cup holes when you build the telephone.
A torch test needs a shared meaning too. Agree on a flash pattern before sending it. Ask your friend which message they understood. If they saw the flashes but understood something else, check your agreement. If they could not see the flashes, move closer.
Use a small battery torch below face level. Do not use a laser or shine light into eyes.
2 · Watch
Take it off screen
Where it sits
Learn first
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.