A model made from a cut off soda bottle, a rubber stopper and "Y" tube, two rubber balloons and a sheet of thin rubber can provide a visual representation of the respiratory system. The rubber stopper and "Y" tubing represent the mouth, trachea and bronchi, while the balloons attached to the "Y" tube represent lungs. The bottle itself acts as the chest and the rubber sheet stretched across the bottom of the bottle forms a diaphragm. When the rubber sheet is pulled down, a vacuum forms, drawing air through the "Y" tube into the balloons, simulating inhalation. Releasing the rubber sheet simulates exhalation.
Cut the bottom of the 2 L soda bottle away with the scissors. Remove the label from the bottle. Insert the rubber stopper into the mouth of the bottle.
Place the mouth of one of the small balloons over one of the forked tubes on the "Y" tube. Attach the balloon tightly to the tube using a rubber band. Attach the other balloon to the other end of the forked tubes in the same manner. Insert the stem of the "Y" tube into the hole in the rubber stopper on the inside of the 2 L soda bottle.
Stretch the sheet of rubber across the opening where the bottom of the 2 L soda bottle was. Place a rubber band around the bottle to hold the sheet tightly in place and form an airtight seal.
Grasp the rubber sheet in the centre between your thumb and forefinger. Pull the sheet downward to simulate inhalation and release the sheet to simulate exhalation.
If you do not have a "Y" tube, a single tube can be used to represent just one lung.