[SciShow Kids intro plays]

Jessi: It might look like we’re having a party, but we’re actually conducting an experiment! Squeaks and I are experimenting with balloons, to see what happens when we try different things with them. Like blowing them up—and then letting them go! Want to join us?

Before we get started, let’s think ahead: Other than balloons, what do you think we’ll need? That’s right! Air! I used air to blow up all of these balloons around me, just like I’ll use air to blow up this balloon. There. Ta-da! Even though we can’t see the air around us that we breathe, it takes up space. And when we put air inside of something—like this balloon—it takes the shape of whatever container is holding it.

Now, once I blow up a balloon, what do you think will happen if I let go of it, and let the air out? Will its shape change? Will it drop to the ground? Or will something else happen? There’s only one way to find out!

You ready, Squeaks? OK! 1...2...3...let go!

So, what happened to the balloon? It flew out of my hand, zipped around a little bit, before falling to the ground! And how does it look now? Letting the air out definitely changed its shape, but did you notice what happened right after I let it go? It didn’t head straight for the ground -- it flew up and around before finally falling down.

That’s because the air rushing out of the balloon from the bottom forced it to move through the air in the opposite direction. So, if letting go of a full balloon makes it fly around the room, what would happen if the balloon were attached to something? Let’s see how we can use balloon power to make a rocket! All you’ll need is some string, a straw, some tape, and a balloon. And... maybe a friend, or a brother or sister, or a grown up to help you.

First, tie one end of the string to something big and heavy, like a chair, or a table, or a door. Now, put the other end of the string through the straw, and tie that end of the string to something heavy, too, so that the string makes a flat, straight line. Your rocket is almost finished! Now, blow up the balloon about half-way, and pinch the end, so the air doesn’t escape! You might need someone else to help with this next part, tape the balloon to the straw, like this! Now, prepare for launch! Are you ready? And, blast off!

So, what happened?! Well, we just saw force in action! Forces are pushes and pulls, and they’re what make things move. In this case, the air rushing out of the balloon pushed the straw forward, making it move. And this doesn’t just work with rockets made of straws; you can make a balloon-powered car, a boat, or even a balloon-powered airplane with the right materials!

Now, try changing things up a little bit, and see if your rocket behaves differently. Try blowing up the balloon even more next time! Do you think your rocket will go farther, or not as far? Will it go faster? Or slower? Keep experimenting with your rocket, and find out what you can discover about balloon power!

And remember, if you have a question about anything you’d like to learn more about—or make —just let us know by getting help from a grown up, and leaving a comment for us below or send us an email at kids@thescishow.com. We’ll see you next time!