Lungs

Students created a model of lungs using a water bottle, and two large balloons.  The larger balloon is cut at the neck.  Then stretched across the base of a water bottle which has the bottom 2 inches or so cut off.  This becomes the diaphragm.  Another balloon is stretched over the top of the bottle.  To simulate inhale, pull on the diaphragm.  Air is pulled into the smaller balloon and it fills with air.  When the diaphragm is released, exhale, the air is released.

Then students examine lung capacity.  One way to do this is to have students blow into a balloon and measure the circumference of the balloon.  The charted the data and compared with classmates.    

The discussion lead students to ask what type of physical activities they were involved in, and did that affect the size of the balloon.  They also discovered that students that played a musical instrument had a larger lung capacity.