Your lungs are amazing. Located in your chest, your lungs allow you to breathe.

When you breathe in (inhale), air travels from your nose and mouth, down tubes called the trachea and bronchi into your lungs as they expand. The air fills tiny air sacs called alveoli in your lungs. The oxygen from the air then passes to tiny blood vessels nearby, which are called capillaries. This oxygen-filled blood is then delivered to your heart and throughout your entire body. At the same time, carbon dioxide gas that has traveled in your bloodstream moves into those same air sacs. When you breathe out (exhale), your lungs release the carbon dioxide gas, along with some of the air you inhaled. Our lungs can’t do this on their own. The rely on a muscle in our bodies called the diaphragm that helps make this all happen.

In this activity, learners will make a model to show how this organ works. This activity will take about 5-10 minutes of preparation followed by 15-30 minutes of learning time. It is best suited for children in upper elementary and middle school grades. Younger learners may need help and adult supervision with cutting and preparing the materials.

Materials:

• Sturdy plastic cup (alternatively use a sturdy plastic bottle with the bottom cut off and cap – 20-oz. or 1-liter are easier to handle, though a 2-liter bottle will also work)
• 2 small balloons
• 1 large balloon
• Scissors
• Tape
• 2 disposable straws
• Drill (optional)

Directions:

1. Prepare your lung parts

Drill a hole into the bottom of your cup just large enough to fit the straw. If you don’t have a drill, you can use scissors and a pen to make the hole. Make sure there is a tight seal around your straw. If using a plastic bottle, drill the hole into the cap. This hole will represent your nose and mouth.

Cut the neck off the 2 smaller balloons. These are your lungs.

Cut one straw into two equal pieces that are about half the height of your cup. These will be your bronchi.

2. Make your lungs

Tape your two “lung” balloons onto your “bronchi” straws. Be sure everything is tightly sealed; we don’t want your lungs losing air!

Take your other straw and cut it so that it is about the same height as your cup. Make about a 2-inch cut on one end of the straw so that it is split in half. This straw is your trachea.

Insert your “bronchi” straws into the split end of your “trachea” straw so that they make a “Y” shape and tape the straw connections. Again, make sure that seal is tight!

3. Connect your lungs

Cut about a 2-inch slit on the top of your trachea straw so it is split in half. Put your lungs into your cup or bottle and poke the top part of the trachea through the hole. Push the straw through until your lungs are completely inside the cup

Cut the top part of your trachea straw lengthwise again to create 4 slits. Fold the slits down around the cup and tape them to hold them down

4. Make the diaphragm
Stretch out the large balloon and tie it. Cut the top off the balloon.

Stretch the tied part of the balloon over the bottom of your cup. You may need to work with a partner on this step. You now have a fully functioning lung model

5. Modeling breathing
Gently pull down on your diaphragm balloon and observe what happens to your lung balloons inside. Let go of the diaphragm balloon. What happens to your lungs now

What is happening?
As you pull down on the diaphragm, you increase the amount of space around the lungs. This causes air from the outside to rush into the lungs making them expand (the inhale). When you release the diaphragm, the amount of space around the lungs decreases, causing all the air to be pushed out of the lungs as they go back to normal size (the exhale).

How to adjust for younger and older learners

For younger learners, make this a family project! Instead of making two balloon lungs, you can make the model using just one balloon lung and a single straw. It will work exactly the same and will take a shorter time to build. Ask young learners questions such as, “What do you feel when you take a deep breath in? What about a deep breath out?”

For older learners, research various conditions or diseases that can affect breathing. Design and build a lung model that represents your lungs under that condition. How does your new model function differently than your original lung model?

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