MCEureka! Science Experiment Balloon Lungs

  • Experiment
  • Science
by Marshall Cavendish Education | Jun 28, 2018

Ever found yourself stumped for words when your child asked how the human respiratory system works? Let us show you how this can be explained with a simple Science experiment!

Materials needed:

  • A plastic bottle
  • Two straws
  • A pair of scissors
  • Three balloons
  • A packet of blu tack
  • A roll of scotch tape

Let’s begin!


Step 1: Cut off the bottom end of the plastic bottle.

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Step 2: Cut a hole about 5cm away from one end of the first straw.

Step 3: Cut a 5cm piece from one end of the second straw and insert it into the hole of the first straw such that it looks like an inverted “Y”.

 BL image 2

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Step 4: Use blu tack to keep the straws in place. Ensure that the straws are not crushed so that the air can flow.

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Step 5:  Attach one balloon to the end of each straw using tape. You will see a simple ‘lung’ structure being formed.

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Step 6: Insert the straw structure through the mouth of the bottle. Use blu tack to fully cover the mouth of the bottle. Again, ensure that the straw is not crushed so that air can flow.

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Step 7: Take another balloon and cut half of it before tying a knot at the end.

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Step 8: Stretch the cut balloon over the base of the bottle until it fully covers the base. Carefully pull the balloon at the base of the bottle downwards and upwards a few times and watch the ‘lungs’ inflate.

So how does it work?

When the balloon at the base is pulled, it creates more space in the bottle. To fill this space, air from the surroundings rushes into the bottle through the straw, inflating the two balloons inside.

Similarly, when we inhale, our diaphragm (represented by the balloon at the base), tightens and moves down. This creates more space in our chest, allowing air to enter though our mouth and nose, flowing down into our windpipe (represented by the straw) thus inflating our lungs. When we exhale, our diaphragm moves upwards, constricting the space in our chest and causing air to be forced out of our nose and mouth.

Watch our video and try this experiment today!

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