Today is rung 4 of 5 on this topic
Waves, and how information travels
Can do: Describes waves by amplitude and wavelength, and explains how sound and light carry information.
Why it matters
It links physics to everything a child uses daily — wifi, phones, headphones — and makes an abstract idea concrete.
What it looks like when it's wobbly
No mental model for how a message gets from one place to another without something physical crossing the gap.
⏱️ Two-minute check
"How does your voice get to Grandma's phone? What's actually travelling?"
Solid looks like: Some chain: vibration to electrical signal to radio wave and back.
The full activity for this topic · 20 minutes
Rope Waves and String Phones
- 1Shake a rope and make waves. Show amplitude by shaking harder, wavelength by shaking faster.
- 2Drop a stone in water and watch circles spread — the water doesn't travel, the wave does.
- 3Build a string telephone and talk through it. Feel the string vibrating.
- 4Test what breaks it: slack string, touching the string, going round a corner.
- 5Invent a code — long and short pulls — and send a message. That's digital signalling.
If it's too hard
Just the rope and the water bowl.
If it's too easy
Send a full word in a two-symbol code and time how long the message takes.
Say this
"The water isn't moving across the bowl — watch a leaf. So what is moving?"