Editing Bottle Diaphragm

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Biology]]:
| Respiration
|-
| Grade Range:
| [[Elementary School]], [[Middle School]]
|-
| Format:
| [[Hands-on]]
|}

The Bottle Diaphragm is easy to build and easy to present to students. For large events, bring 1-3 finished bottles for students to play with. For small groups, you can choose to bring enough supplies for every student to make their own!

== Materials ==

* Balloons
* Straws
* Rubber Bands
* Sandwich Bags
* Duct Tape
* Scissors

== Safety Precautions ==

Please read the General Safety Precautions section of the [[Demonstration Safety]] page before performing this demonstration.

== 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?

== Why This Works ==

''Respiration'' is the action of breathing. One might already know that to breathe they use their lungs, but the lungs don't do the inflating by themselves. The lungs get help from another muscle called the ''Diaphragm'', which is a big flat muscle right below the lungs. When you breathe in, the diaphragm pushes down, and causes the area inside the lungs to expand and have a drop in pressure. This pressure drop is how air is pulled into our lungs, and how our bodies can get the oxygen they need. When the diaphragm relaxes, it moves back up and the area inside the lungs returns to normal. This causes an increase in pressure and is how our bodies breathe out, expelling carbon dioxide and other gases.

== Additional Information ==

* This demonstration pairs well with the [[Classroom Digestion]] demonstration.