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Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, and Judith Dresden, MS.

Modeling the Lungs

About the Model
The breathing machine model shows students how changes in pressure draw air into the lungs. However, there are several differences between real lungs and the model.

Humans Have Two Lungs

  • Lungs actually fill the entire space available within the chest.
  • Each lung has a spongy appearance inside, instead of being hollow.
  • The thin space between the lungs and the chest wall is filled with liquid. 
  • The chest cavity itself is divided into two spaces, one for each lung.

Complete instructions for conducting activities in this slide set, including materials needed, setup instructions, student sheets (in English and in Spanish), answer keys and extensions, can be found in The Science of Air Teacher’s Guide, which is available free-of-charge at


1. Begin by asking each student to notice his or her own breathing. Ask, How many times are you breathing per minute? How can you tell? Which parts of your body move when you breathe? Tell students that they will make a simple model to investigate how air moves in and out of the body.

2. Have the Materials Managers pick up prepared plastic bottles and balloons for their groups.

3. One student from each group should slide a balloon into the top of the bottle and roll the open end (mouth) of the balloon over the top edge of the bottle.

4. Another student should cut off the bottom of the second balloon and tie a knot in the stem (mouth) of the remaining piece. While one student holds the bottle, another should slide the cut end of the balloon around the cut end of the bottle.

5. Ask students to predict what might happen when the bottom balloon is pulled downward. Have students try pulling the bottom balloon gently. Ask, What happened to the top balloon? Point out that this is similar to what happens when each of us breathes in.

6. Next, direct the students to squeeze the sides of the bottle gently while pushing the bottom balloon into the space in the bottle. Ask, What happened?

7. Using the diagram on page 8 of the Air unit’s Explorations magazine, help students understand that the balloon inside the model represents our lungs and that the bottom balloon represents our diaphragm. Discuss ways in which their models are similar to and different from the actual respiratory system.

8. Have students stand and take a deep breath. They should be able to notice that their chests expand when they inhale and contract when they exhale.

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education