Make Lungs

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life sciences,
physical sciences






one class period


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for educational use.


Students will learn how ... a lung works by making a biomechanical [definition] model.

Background Information

To breathe, your lungs work together with your diaphragm. When you breathe in, muscles [definition] attached to your rib cage and diaphragm work together to draw air through your windpipe into your lungs. When you breathe out, most of the rib cage and diaphragm muscles relax and your lungs deflate.

This activity gives your students a closer look at how your diaphragm and lungs work together when you breathe.



For each team of students:

  • Top half of a plastic soda bottle.
  • Ballpoint pen barrel.
  • 2 balloons.
  • Rubber bands.
  • String.
  • Modeling clay.
  • Tape.
  • Scissors.

diagram for making a model lung


Watch your chest as you take a deep breath.

Place your hands on your abdomen just below your ribs and feel what happens when you take another deep breath. What did you feel?

How does your body breathe?


  1. With a rubber band, fasten a balloon to the end of the ballpoint pen barrel. This is the "lung."
  2. Position the tube in the neck of the bottle, and make an airtight seal with modeling clay.
  3. Cut across the other balloon and use it to seal the bottom of the bottle. This is the "diaphragm."
  4. Fasten the string to the balloon with the tape.
  5. When you pull gently on the string, the air pressure inside the bottle falls. Air from the outside then flows into the intact balloon and it begins to inflate. This is just what happens to your lungs when your diaphragm contracts.
  6. If you let go of the string, air pressure inside the bottle rises. Air is forced out of the balloon. It quickly deflates, just as your lungs do when you breathe out.


What happened when you pulled down on the diaphragm?

What happened when you released the string and let go of the diaphragm?

How does this compare to how your lungs and diaphragm work together?

How does creating a biomechanical model help you understand what's going on inside you?

Adapted from

Burnie, David. How Nature Works. Pleasantville, NY: Readeršs Digest Association, Inc., 1991.

Additional Sources

Whitfield, Philip, ed. The Human Body Explained. First ed., New York: Henry Holt and Company, 1995.