Communication Device Builder

Pick a flashlight, drum, or cup phone, then design a pattern of pulses to send a message. Watch and listen to what the receiver picks up. Learn how light, sound, and vibration carry signals over distance.

Score: 0

Choose your device

Flashlight. Shine pulses of light to send messages far away. Range: Across a dark room.

Light receiver

Pattern length5

Tap each cell to turn the signal on or off.

Receiver hears: 1 flash, pause, 1 flash, pause, 1 flash

That is the pattern for "Hello"

Try a preset message

Reference Guide

How Devices Send Messages

  • Flashlight. Sends flashes of light. Light travels very fast and works best in dark places.
  • Drum. Makes loud beats. Sound travels through the air as invisible waves.
  • Cup Phone. Two paper cups joined by string. Your voice shakes the bottom of one cup, and that shaking travels as vibration along the string to the other cup.
  • Pattern. The order of pulses and pauses is what carries meaning.

Light, Sound, and Vibration

  • Light travels in straight lines and moves very fast.
  • Sound is a vibration that spreads through air, water, or solid objects.
  • Vibration is a tiny back and forth wiggle that can carry a signal.
  • People can plan patterns so others understand the message.
  • Standard covered. 1-PS4-4.

Example Patterns

  • Hello. Three quick pulses. Works on any device.
  • Come Here. Two pulses, a pause, then two more.
  • SOS. Three short, three long, three short. A famous call for help sent by flashlights or drums.
  • Yes. Two quick pulses. Best for drums and cup phones.
  • No. Three pulses in a row. Easy to drum or tap.

Try This

  • Design your own pattern and tell a friend what it means.
  • Try sending the same message with two different devices. Which travels farthest?
  • Switch to Challenge mode. Match the target message exactly.
  • Long signals feel different from short ones. Plan your pattern so the receiver can tell them apart.