Editing Bottle Diaphragm (section)

== Demonstration ==

;Preparation:
* Use a rubber band to attach a balloon to the end of a straw. Repeat, and then attach the two straws together using a rubber band.
* Cut off the bottom of the bottle, removing no more than 1/4 of the bottle's total height. Stick the straws up through the center of the bottle, far enough to have the balloons fully within the bottle. Duct tape the straws to the mouth of the bottle, making sure to fully seal the top of the bottle with the duct tape.
* Open a sandwich bag and put the bag inside the bottom of the bottle. duct tape the lip of the bag to the bottle rim, being sure to seal it fully. If fully sealed, you should be able to pull on the sandwich bag and see the balloons inflate inside the bottle!

;Presentation:
# As students come up, hand them the bottle and ask them to pull gently on the sandwich bag. When they do, they will see the balloons inflate! Have students let go of the bag, so they can watch the balloons deflate themselves. 
# Ask students for ideas on why it works. What is causing the balloons to inflate? Also ask students if they know how their lungs work. Can they see the connection to this demonstration?