A red balloon taped to a straw zooms along a string when the air is let out the back.

Ages 9+ | 20 min | Experiment | Screen Free

How fast can you make your balloon rocket go?

Build a balloon rocket to explore rocket propulsion—the force that pushes rockets forward!

What You'll  Need: 

  • 1 balloon
  • 1 drinking straw
  • String: Dental floss, fishing line, or smooth yarn
  • Tape
  • Scissors
  • Two things to tie the string to, like two chairs, a doorknob, a hook on the wall, etc.
  • Optional: A few coins for cargo
  • Optional: Clothespin or chip clip

Instructions

1. Thread the straw onto the string.

A string runs through a paper straw.

2. Tie the string between two points so it's tight and straight.  

Tip: A good distance for your balloon rocket launch is across a room or down a hallway. One end of the string will be the starting point. The other will be the end. 

An illustration of a string with a straw on it tied between two chairs.

3. Blow up the balloon and pinch the end.  

You can use your fingers or a clothes pin or chip clip. Do not tie it. 

All illustration of an inflated balloon with a clothes pin on the end

4. Tape the balloon to the straw so the opening points straight back on the string towards the starting point. 

5. Predict what will happen. When the air goes out, where will the balloon go?

An illustration of an experiment set up where a string stretches between two chairs, with a straw on the string. An inflated balloon with the end pinched closed is taped to the straw.

6. Count down and let go! 

Caution: Keep the balloon opening pointed away from faces. Make sure no one is standing in the path of the balloon when it launches.

7. Notice: What did you see? What sound did the air make? Was your prediction correct? 

Tip: If the rocket slows or sags, tighten the string or try a smoother string like dental floss or fishing line.

An illustration of an experiment set up where a string stretches between two chairs, with a straw on the string. An inflated balloon with air coming out is taped to the straw.

Try some different tests

1. Change how much air you put into your balloon.  
What happens when you make your balloon bigger or smaller?

2. Choose a goal. 
Can you make it go further or faster?

3. Add "cargo" or "people." Tape a couple of coins to your balloon then launch it?  
What happens when you add weight to your balloon? What do you notice that's different?

An illustration of an experiment set up where an inflated balloon with coins on it is taped to a straw. The straw is on a string which is threaded between two chairs.

We want to hear from you!

Optional
The pitch black night is illuminated by a bright white-hot rocket engine plume, which illuminates clouds of smoke surrounding the launch pad.

How is the balloon rocket like real rockets?

  • Action-reaction: Both the balloon rocket and big rockets move by pushing gas out the back so the rocket goes forward. This is called action-reaction.
  • What’s pushing out: The balloon uses compressed air that rushes out of the opening. Real rockets burn fuel to make very hot gas that shoots out of a nozzle very fast to create strong thrust.
  • Staying on course: The string and straw keep the balloon moving straight. Real rockets use guidance and control systems to stay on the right path.
  • Working in space: Neither the balloon nor real rockets need to “push off” the ground or air. Pushing gas one way makes the rocket go the other way, even in space.
  • Big differences: The balloon’s push is brief and small (just air pressure). Rockets NASA uses to send people to space carry huge fuel tanks. They often have multiple fuel tanks that fire at different times. This is so they can keep pushing long enough and hard enough to reach space.

About This Learning Resource

Age and Grade Level

Age: 9-12

Grade Level: 3-5

Subject

Engineering

Spaceflight
Spacecraft
Rockets

Duration

20 mins

Usage Rights

You are free to use this resource for personal and educational purposes, with attribution. (CC BY-NC)

A young visitor constructs an eclipse viewer while helped by his guardians and museum staff.

Soar Together

Soar Together offers family days at the National Air and Space Museum's two locations, as well as activities like this one for families to do anywhere. 

Soar Together is made possible by the generous support of the Northrop Grumman Foundation.

More About Soar Together

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