DIY Lung in a Bottle: Science Experiment & Lesson Plan for Kids

Teach kids the science of breathing with this engaging, hands-on lesson plan. Using a plastic bottle and balloons, students will build a working DIY lung model to visually understand how we inhale, exhale, and how the diaphragm works. This step-by-step guide is perfect for elementary school teachers and homeschooling parents looking for a fun science activity to explain the respiratory system.

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My Amazing Lungs: A Breathing Adventure!

Materials Needed:

  • One clear plastic bottle (like a 16-20 oz soda or water bottle)
  • Two standard-sized balloons (different colors are fun!)
  • One larger balloon
  • A flexible or bendy drinking straw
  • Modeling clay or Play-Doh
  • Scissors or a craft knife (for adult use only)
  • Strong tape (like packing or duct tape)
  • Optional: A simple diagram of the human torso, markers or crayons

1. Learning Objectives (The Goals)

By the end of this lesson, the student will be able to:

  • Demonstrate the difference between breathing in (inhaling) and breathing out (exhaling).
  • Explain in their own words that lungs fill with air, similar to a balloon.
  • Construct a simple, working model of a lung and demonstrate how it functions.
  • Point to the general area of the chest where the lungs are located.

2. Introduction: The Breathing Detective Warm-Up (5 Minutes)

  • Activity: Start by saying, "Let's be breathing detectives! Put your hands on your chest. Now, take a really big, deep breath in... and let it all out with a big whoosh!"
  • Discussion: Ask questions to spark curiosity:
    • "What did you feel moving under your hands?"
    • "Did your chest get bigger or smaller when you breathed in?"
    • "That amazing feeling is from a special part of your body called your lungs! They are like two balloons inside your chest that help you breathe all day and all night."
  • Connection: "Let's try blowing up one of our balloons. See how it gets bigger when you fill it with air? Your lungs do the exact same thing!"

3. Main Activity: Let's Build a Lung! (15 Minutes)

This hands-on activity creates a visual and physical model to explain an invisible process. Note: The adult should handle all cutting.

  1. Prepare the Bottle (Adult Task): Carefully cut the bottom off the plastic bottle, about an inch or two from the base. Discard the bottom piece.
  2. Prepare the "Lung" (Student Task): Ask the student to place the straw about two inches into the neck of one of the standard-sized balloons. Securely tape the balloon opening around the straw so no air can escape. This is your "lung" and "windpipe."
  3. Assemble the "Chest" (Student Task): Guide the student to lower the balloon-on-a-straw into the bottle, feeding the top of the straw out through the bottle's mouth.
  4. Seal the Top (Student Task): Use the modeling clay or Play-Doh to create a seal at the mouth of the bottle, holding the straw firmly in place. Ensure the seal is airtight.
  5. Create the "Diaphragm" (Adult & Student Task): Cut the neck off the larger balloon to create a flat rubber sheet. Let the student help you stretch this sheet tightly over the open bottom of the bottle. If needed, use tape to secure the edges of the balloon sheet to the bottle. Your model is complete!

4. Application & Discovery: How Do Our Lungs Work? (10 Minutes)

  • Demonstration: Hold the bottle and say, "This model is just like your chest! The bottle is your rib cage, the balloon inside is one lung, the straw is your windpipe, and this bottom balloon is a super-strong muscle called the diaphragm."
  • Hands-On Exploration: Let the student gently pull down on the knot of the bottom balloon (the diaphragm).
    • Ask: "What happens to the lung balloon inside when you pull down?" (It inflates!)
    • Explain: "That's exactly right! When you breathe in, your diaphragm muscle pulls down, making space for your lungs to fill up with air."
  • Connect and Compare: Now, have the student push the bottom balloon up into the bottle.
    • Ask: "What happens now?" (The lung balloon deflates!)
    • Explain: "Perfect! When you breathe out, your diaphragm relaxes and pushes up, gently squeezing the air out of your lungs."
  • Practice: Encourage the student to play with the model, pulling and pushing the diaphragm while you both take deep breaths in and out, connecting the model's action to their own body.

5. Assessment & Wrap-Up: Show and Tell (5 minutes)

This is a gentle check for understanding through creative expression.

  • Show Me: Ask the student, "Can you point to where your real lungs are on your body?"
  • Tell Me: Ask, "Can you use your lung model to show me what happens when you breathe IN? What about when you breathe OUT?"
  • Draw It: Give the student paper and crayons. "Can you draw a picture of your lungs? What do they do?" Encourage them to draw big balloon shapes inside a person. This helps solidify the concept in their mind.

6. Differentiation and Extension (Making it Simpler or Adding a Challenge)

  • For Extra Support: If the model is too complex, focus just on the breathing exercises and blowing up balloons. Talk about how our bodies need air to run and play. Use simple language like "lungs get big" and "lungs get small."
  • For an Extra Challenge: Introduce the idea that we have two lungs. Ask, "Why do you think we need to breathe? What is in the air that our bodies need?" (Oxygen). You can also do a simple experiment: run in place for 30 seconds and then notice how your breathing changes (it gets faster because your body needs more oxygen!).