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  • Writer's pictureMade by Ellie C.

Balloon Lung Model

Updated: Jul 25, 2021

In this craft, you can create a simple model of a human lung that demonstrates how breathing works using just a couple of balloons and a water bottle. School-aged children and adolescents interested in the function of the human anatomy can take part in this activity to learn how their own body makes them breathe. With one balloon as a lung and the other as the diaphragm, this hands-on model can be used to demonstrate the diaphragm’s role in breathing. The model you create will have a balloon at the top and another at the bottom so no air will be able to go into or out of the bottle. Now, let’s make a hypothesis, that’s a guess about what will happen and why based upon what we already know.

What do you think will happen to the top balloon when you pull on the bottom one? How do you think this represents your own lungs and diaphragm?


-2 Balloons

-An empty water bottle


-Masking or duct tape

-An adult helper

-*Optional* Nail file or sandpaper

Activity Steps:

Before getting started: Make sure you have gathered all of the materials on the list! This won’t be a messy activity, so any area with a flat surface to set supplies works!

Step 1: For this first step, you will only be working with the water bottle. If it still has a cap on it, go ahead and remove it and set it aside. You will not need the bottle cap for this activity, so if yours doesn’t have one you’re all good! Next, find a point about one to two inches from the bottom of the bottle and have an adult carefully cut around the bottle so that the bottom is completely removed. The top section is what you will work with, so feel free to recycle that bottom part that was cut off. If you have a nail file, you can have an adult carefully smooth out the cut edge of the bottle so that there aren’t any sharp pieces of plastic sticking out.

Step 2: Now, pick one of the balloons and push the bigger end of it into the top of the bottle. Take the opening, the part that you would usually blow air into, and fold the edges of it over the top of the bottle. The bigger part of the balloon should hang inside. After the lip of the balloon is folded over, tape around the edges of it. We want to make sure that this is sealed well and that air cannot escape!

Step 3: Next, take the other balloon and tie a knot in the end of it. Once the balloon is tied, cut it in half horizontally.

Step 4: Now, take the half of the balloon that has the knot and pull the cut edge of it around the open bottom of the water bottle. If it doesn’t fit at first, try stretching the balloon out a bit before fitting it over the bottle. After the balloon is around the bottom, tape it in place securely. We don’t want any air to get through on this end either!

Your model is now finished! Let’s go back to the hypothesis you made before starting this activity. Look at the craft and think about how we said this model would work like a lung and diaphragm. Now that you have completed the model, do you want to change your hypothesis at all? What do you think will happen to the balloon inside the bottle if you pull down on the tied balloon at the bottom?

Step 5: While keeping your hypothesis in mind, try pulling down on the knot in the balloon. When you pull down on the bottom balloon’s tie, what happens to the balloon inside the bottle? Gently release the knot and watch the balloon inside. What happens to it now? What differences do you see? Take a minute to think about the two balloons. How do you think this model represents your lungs?

Step 6: Try pulling the bottom balloon out and pushing it into the bottle different amounts and at different speeds and look at how the top balloon reacts. The top balloon represents a lung and the bottom balloon represents a muscle called the diaphragm. The diaphragm is the muscle that sits below your lungs and helps them inflate and deflate with air, just like the balloon! When your diaphragm pulls down, your lungs fill with air and you breathe in, and when it pushes up they deflate and you breathe out! Of course your body has two lungs and this model only represents one, but the function is the same! Now you can teach your friends and family about what their diaphragm does using your very own homemade model!

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