paper cup telephone experiment worksheet

Make a Paper Cup Phone

January 31, 2019 by OneMommy

It seems everywhere you look people are talking about STEM activities for kids .   Not only do the activities get kids thinking about science, technology, engineering, and math, but kids genuinely love STEM challenges .

This week we had fun with a classic STEM activity : making a paper cup phone , something I remember doing as a child.

Affiliate links have been provided below. See my full disclosure here . 

Making a cup phone is a fun way to learn about the science of sound.  You might also want to try this simple sound experiment .

Paper Cup Phone

Materials Needed: 

• 2 paper cups
• 20 feet of string (We used yarn.)
• Sharpened Pencil
• 2 Paper clips (optional)

To make your own cup phones, use the tip of a pencil to poke a small hole at the bottom of each of your two cups.

Next, thread the string through the hole of one cup.  We just tied a knot in the yarn on the inside of the cup to keep it in place.  If the string keeps slipping through the hole you can tie it to a paper clip to help keep it in place.

Pull the string through the bottom of your second cup, securing it with an knot on the inside, too.  (See photo above.)

To use your cup phones the string must be kept taut.  When one person whispers in their cup, the other should be able to hear their voice through their own cup.

My daughter was thrilled to hear my voice being whispered in her ear from over 20 feet away!

You can even try whisper singing into the cup, turning it into a musical STEM activity .  

Related post: STEM Challenge: Build a Boat that Floats

Why does the string and paper cup phone work?

Sound waves can travel through air, solids, and liquids.

When you speak into the cup, the vibrations are transmitted into the string.  They continue to travel through the string, as long as it is held taut, to the receiving cup.  There the vibrations are transmitted to the air in the cup, around the listener’s ear, allowing the whisper to be heard.

Because the cup and string are solid, and solids actually carry sound waves better than air, the whisper can be heard much clearer than if you were to just whisper into the air from that distance.

Take your cup phone activity further!

Have your child try one or more of the following extension activities:

• Use a longer piece of string.  Does the homemade phone still work if the string is 40 feet?  How about 60?
• Try making the phone with plastic cups or tin cans.  Which phone works the best?
• Replace the string with wire.  How does this affect the phone?

You kids will have fun learning how to make a paper cup phone! 

You may also like:

• Music STEM 
• STEM Challenge: Design a Boat that Floats
• STEM Challenge: Craft Stick Catapults
• STEM Challenge: Build a Stuffed Animal Chair
• Old-Fashion Fun with Tin Can Stilts

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March 1, 2015 at 4:12 pm

That was one of my fav things to do as a kid! I would use one to go form my neighbors house to mine. I would use it also from the top bunk bed to the bottom for fun lol!

OneMommy says

March 3, 2015 at 11:04 pm

I love the idea of going from bunk bed to bunk or to a neighbor’s house! We need to use a longer piece of yarn!

susen @Dabbling Momma says

March 1, 2015 at 10:20 pm

fun!! Gonna give it a try.

March 2, 2015 at 1:38 pm

It is definitely old school. Now, I have to head your way to check out that Dr. Seuss CVC word hunt!

March 2, 2015 at 1:37 pm

It is such a classic. Now, I see your last post was Dr. Seuss related, so I am definitely heading over to check it out! 🙂

March 3, 2015 at 12:06 pm

Ah, this takes me back. When I was little my best friend/next door neighbour and I would make these and talk from our bathroom window to her bedroom window and think how clever we were! It was about 15 foot and we could just as easily shout but this was WAY more fun!

[…] of; it's actually one of those science activities which completely blows my mind! And I love this paper cup telephone activity, always amusing for children to […]

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Make a Cup Phone | STEAM Activity for Kids

by Emily | May 14, 2020 | STEAM Experiments , STEAM for Kids | 0 comments

Today’s STEAM Activity is the classic cup phone! We rarely talk on the phone at my house anymore. I more often text or FaceTime with friends and family. So my kids are not really familiar with phones (and especially phones with cords) like I was growing up. But that didn’t affect their enjoyment of this simple activity. 

• Two paper or plastic cups
• String 

• Measure and cut 20 feet of string. We practiced math while measuring (look in the Math Concepts section below for how we measured the string)

2. Use your scissors, or something sharp to poke a small hole in the bottom center of each cup

3. Poke the string through the hole on the cup and tie a double knot to keep it from coming back through the hole. Note : A double knot worked well for us because our hole was small. If a double knot doesn’t hold your string inside the cup, try tying the string to a toothpick that is laying horizontally inside the cup to prevent the string from pulling through.

4. Repeat on the second cup, using the other end of the 20′ string

5. Have one person hold each cup and stand 20’ apart (you need the string pulled tight)

6. One person holds the cup to their ear and the other holds it over their mouth. The person with the cup over their mouth can talk quietly or whisper into the cup and the person listening will hear it loud and clear!

7. Switch who is listening and who is talking and try again. We had so much fun with this. We even tried it around a corner so the people talking and listening couldn’t see each other!

STEAM CONCEPTS LEARNED:

• Science : Sound vibrations can travel through air, solids, and liquids. In this case our sound vibration travels through the string and into the air inside the cup, so you can you hear the whisper from the other side of the room. Sound waves travel better through solid conductors like the string and cup, which is why you hear the whisper more clearly than if you didn’t use this phone. 
• Math : We practiced simple multiplication while measuring the 20’ of string. Here’s how: we had a 12” ruler. 12”= 1’. We measured 1’ five times, 1’*5=5’. We doubled the 5’ section, 5’*2=10’. We doubled the 10’ section, 10’*2=20’. This was a fun hands-on multiplication lesson for my son!
• Art : Can you decorate your cups to make them as beautiful as they are functional? It’s like getting a pretty case for your cell phone. 

This is too easy for you to not try right now! Go do it with your kids and let me know how it goes! Do you kids know how to use a phone, or do they only FaceTime like my kids?

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Hi, I’m Emily. I’m an engineer, mom, and wife. I encourage kids to love STEAM and motivate women to find personal happiness in their career and motherhood journeys.

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String Telephone Explanation: How Sound Waves Travel

Learn all about sound in this super-fun science twist on the classic tin can telephone activity. This version is even more kid-friendly because it uses Styrofoam cups. After making your string telephone, read the  string telephone explanation with your kids to discover why it works!

Learn how sound waves travel in this super-fun science twist on a classic kid’s activity!

You’ll need just a few things for this project:

• Styrofoam or paper cups
• Cotton twine

Use the scissors to poke a little hole in the bottom of each cup.

String a piece of twine between the cups. Use a long piece of string to help the sound travel farther.

Tie a knot in the end of the string to keep it in the cup.

Decorate the cups if desired.

One person can hold the phone up to their ear and the other person can talk into the other cup. Keep the string tight or the sound waves won’t travel correctly.

String Telephone Explanation

Sound waves are created when sounds make vibrations in the air. In this activity, your voice vibrates the air inside the cup, which are then transferred to the bottom of the cup. The bottom of the cup passes the sound waves to the string, and so on to the other cup. You can hear surprisingly far using a string telephone if help the right way!

If the string is kept tight, the sound waves will travel. If the string is loose, the sound is less. This is because the lose string causes the vibrations to travel all around rather than directly down the string. Try experimenting with different lengths of string, types of string, and types of cups to see which produces the best sound over the longest distance.

Old landline phones were created using the same principle as a string telephone. The sound waves are turned into an electrical signal that can travel much farther than a simple string.

What other sound activities can you try with your kids after doing this one?  Share your ideas with us!

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Paper-cup Phones Practical

Subject: Primary science

Age range: 7-11

Resource type: Worksheet/Activity

Last updated

28 January 2021

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In teaching the topic of sound and look at vibrations and how sound travels, the children perform this practical. It involves making the paper-cup phones by following the instructions and writing it up using the scientific method.

The equipment and method are done already but the children are expected to select their own hypothesis and write up a short analysis and conclusion.

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Tin Can & String Telephone: A Simple STEM Experiment

What transmits sound better: recycled soup cans or plastic party cups.

Experimenting with tin can or plastic cup telephones can be a great boredom buster for kids! Kids growing up in the smartphone generation will be amazed at how something as simple as STRING can transmit sound.

Granted, tin can phones aren’t the most practical communication device. Since the line between cans needs to be held taut to transmit sound, you’re unlikely to “place a call” farther than down the hall or across the back yard.

Unless…

Worlds Longest Tin Can Phone

The Guinness Book of World Records says the worlds longest FUNCTIONING tin can phone was made in Japan in August 2019. It went 242.626 meters, or 796 feet! That’s almost three football fields long! Sadly, there’s no details on how the phone was made or what materials they used.

If you want a little inspiration before setting up your own backyard experiment, check out this video from 2013 when a few friends set up a tin can phone between two houses over 650 feet apart! Not only is their experiment amazing, but the video is well made and entertaining.

Lots of YouTubers have tried their own tin can phone experiments. Spoiler alert: the Danocracy might SAY they made the world’s longs phone at 1000 feet …but it didn’t work. Does that make it click bait? ¯\_(ツ)_/¯

Supplies for a String Telephone Experiment

First…I want to point out that “tin cans” these days are actually made of steel. Steel cans are lined with either tin or plastic to prevent rust and keep your food tasty. But we still call them “tin cans” out of habit.

A basic string phone can be made with supplies you’re likely to have around the house. If you want to get really scientific, try out a variety of “receivers” and types of string.

You’ll need two cans or cups. These can be recycled soup cans, plastic party cups or paper cups. The cups will help transmit the sound — keep notes and find out which cup works best!

Note: We found Styrofoam cups to be pretty horrible. The material is too fragile when you pull the string tight. Little kids are likely to rip a hole in them.

You’ll also need string, and lots of it! The guys in the 2013 video used nylon twine, which is pretty stout. Of course they were also running their line over 650 feet. Cotton string, fishing line and ordinary twine also work. What else can you try out? Yarn? Dental floss? Sewing thread?

Make a String Telephone for Kids

Conduct an experiment in SOUND with this old school craft!

• 2 Clean Cans or Disposable Cups
• String (at least 25 feet)
• Washer or Paper Clip (optional)

Instructions

• If using a recycled can, work on a a sturdy surface, like a work bench if you have it or a thick plastic cutting board. (Don't hammer on your nice kitchen table!)

• If using a disposable cup, you should be able to poke a hole in the bottom of the cup without a hammer!
• Repeat for both cans or cups. You'll need two!

• Pull the string through the can. Tie a large knot in the string. It needs to be big enough to prevent the string from coming out.
• If your hole is too big, or the string too narrow, tie the string to a washer or paper clip to keep it in place.
• Repeat for the other can or cup.

If you're running this as an experiment, make several phones at once with a variety of materials. You can also try a can on one end and a cup on the other. Which work best? Record your results!

How to Use Tin Can or Cup Telephones

Once you’ve made your telephone, you’ll need two people to run the experiment. Have each person take an end and walk apart until the string is TIGHT. One person then holds the can or cup to their ear while the other talks into their can or cup.

Ideally, you’ll want to stand far enough apart that you can speak normally into the phone and not be heard by the other person. If you can’t get THAT far apart, try a whisper!

Pet Peeve: A lot of stock photos (and blogger photos!) of people using tin can phones are misleading. They show people with the string dangling loosely between the two ends. This WILL NOT work. No wonder that guy looks confused.

They also show people standing right on top of each other. You need a bit of distance for this experiment to really work.

Record Your Experiments

Level up your tin cans from “just another craft” to a fun STEM event by making several phones or swapping out materials. Record your results!

How far did you get? How clearly did you hear the words? Which one was easier to make?

Jot down your findings on a scrap of paper, or use the free printable below. You can also record your experiment using a Voice Recorder app on your smart phone for later comparison.