Active Time
30-45 minutes
Total Project Time
30-45 minutes


We breathe a lot—roughly 12 to 16 times a minute for adults and even more for children! Have you ever wondered how the process of breathing works so smoothly? Our lungs allow us to inhale the oxygen our body needs, but they do much, much more. They also allow us to get rid of carbon dioxide, the waste product created in the body, and they play a vital role in singing, shouting and even giggling. In this activity you will make a model of a lung and use it to discover how air flows in and out of the lungs with ease.


Sabine De Brabandere, PhD, Science Buddies
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.


  • Disposable empty transparent bottle (10–16 fluid ounces) made of hard plastic (such as a sports drink bottle)
  • Ruler
  • Two balloons (8-inch balloons work well)
  • Utility knife (have an adult help and use caution when using the knife)
  • Adult helper
  • Scissors



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Active Time
30-45 minutes
Total Project Time
30-45 minutes
Free science fair projects.