STEM Activity: How Much Air Can Your Lungs Hold?

Have you ever held your breath underwater or tried to sing the longest note in your favorite song? These everyday challenges use the air inside your lungs and can determine just how much air your lungs can hold.

Want to explore the science behind your breath? Just like a scientist, you can build a tool to measure your lung capacity. As you test different variables, your experiment will lead to new findings that might surprise you!

Materials Needed:

• Bowl or large container
• Clear plastic bottle with a lid (2-liter or gallon jug)
• Flexible plastic tube or straw (make sure it’s clean and will fit inside the bottle opening)
• Permanent marker
• Water

Step-by-Step Instructions:

1. Fill the plastic bottle completely with water and screw the cap on tightly.
    
2. Fill a bowl or container halfway with water.
    
3. Turn the closed bottle upside down and place the cap under the water in the bowl.
    
4. Ask an adult to continue to hold the bottle upside down, slightly suspended, so that the cap is hovering above the bottom of the bowl.
    
5. Carefully unscrew and remove the cap, while keeping the bottle opening underwater.
    
6. Slide one end of the clean, flexible plastic tube or straw into the bottle opening while it is still underwater. Keep the other end of the tube above the water.Before placing your mouth on the exposed end of the tube, take a deep breath. Then, place your mouth over the tube end and blow all your air through the tube in one breath. What happens when you exhale into the tube? Where does the water go?
    
7. On the side of your bottle, use your marker to mark how far the water level dropped.
    
8. Repeat the experiment 2–3 times and record your data each time to see what your best results are!

Tip: The bottle opening must stay underwater and off the bottom so the water can flow out when you exhale.

Bonus challenge: Try changing one variable at a time and observe what happens. You could measure your lung capacity before and after exercising, compare your results with a friend or family member, or practice taking slow, deep breaths and test again. What patterns do you notice, and how do your results compare?

What Are We Discovering?

Did you know that your lungs are made up of millions of tiny air sacs that fill with air when you breathe in, and then empty when you breathe out? When you blow air into the bottle, that air pushes the water out and takes up space inside the bottle. This allows you to see and measure how much air your lungs can hold. Scientists call this your lung capacity.

Lung capacity is not the same for everyone. It can vary based on factors like your age and how active you are. As people grow, their lungs grow too, allowing them to move more air in and out. When airways become narrow or inflamed, it can reduce how much air a person can move in a breath. Science helps to solve this challenge!

Understanding lung capacity was important to National Inventors Hall of Fame^® Inductees George Maison, Irving Porush and Charles Thiel, who invented the first portable inhaler that could deliver medicine effectively to the lungs. These devices can make it easier for people with asthma and other breathing conditions to move air in and out of their lungs. By testing and comparing your results, you are exploring how the body works and seeing how experimentation can help solve real-world problems.

Keep Exploring STEM

Ready to discover more everyday STEM? Continue exploring our blog to find hands-on activities that spark inspiration for solving challenges.