Build a Cup Phone

🎂 5 + years ⏱️ 20 min 📍 Anywhere ⭐ medium

It's time for teamwork! Create something really cool: a phone made from paper cups and string. Imagine being able to talk without phones, without screens, just using the power of your voices and a bit of physics. Sounds like magic? It's pure science! And a whole lot of fun on top!

What you'll need

Paper or yogurt cups
Long string 10 to 20 meters
A pair of scissors
Nail or sharp pencil

How it works

First, you need to make a small hole in the bottom of each cup. This is the job for the pencil or nail. But be careful, don't poke your fingers!
Now, thread the string through the hole in the bottom of the cup. Do this for both cups.
To keep the string from slipping out, make a big knot at the end of each string inside the cup. The knot needs to be bigger than the hole in the cup, or it will say 'goodbye' and slip through.
Now comes the exciting part. One person holds a cup to their ear, while the other talks into the other cup. But be careful: the string must be taut, or it won't work!
Magic? No, science! When you talk, you create sound waves in your cup. The sound waves travel along the string and make the other cup vibrate. It sounds like your voice in your friend's ears. Cool, right?
Give it a try. Maybe you'll find even more creative ways to jazz up your cup phone. Glitter? Stickers? Anything goes! And if it doesn't work right away, don't give up. Experimenting is part of inventing.
And who knows, maybe you will be the next great inventors who make a big impact with simple things. So, let's get to the cups!