1. The Lung Model
Lesson 16

2. Instructions: Prepare the following materials:
Plastic balloon
Plastic bottle
Plastic bag
Hard straw
Rubber band
Clay
Cut the plastic bottle in half with a scissor. Observe the proper precautions.
Get a balloon and insert it at the end of the straw. Secure it with a rubber band.

3. Instructions:
Carefully insert the straw through the hole of the bottle. Use a modeling clay to hold it in place and prevent air from entering or leaving.
Stretch the plastic bag under the open bottom of the bottle. Use big rubber bands to hold it in place. Tie a string at the middle of the stretched plastic bag or tie a knot at the bottom.
Pull the plastic bag and observe the balloon attached to the straw change in shape.

5. Answer this…
What happens to the balloon when you push the plastic bag?
What happens to the balloon when you pull the plastic bag?
How do this movement affect the plastic bags?
In respiration what do these movements represents?