First we made model lungs. This would be appropriate for a much younger group but the teens seemed to enjoy it as well.
A balloon makes a better diaphragm but we used a vinyl glove. A glove fingertip is the miniature lung and the stiff cup mimics the stiffness of the chest.
One of the teaching points was that the brain detects a fall in blood oxygen level and then, stimulates a diaphragm contraction that creates an intake of air, or a breath.
So they timed how long they could hold their breath. Then hyperventilated room air, thereby raising their blood oxygen level, and compared how long they could hold their breath again. Each was able to hold it a bit longer.
Then they breathed into a bag, dropping their oxygen level, and could not hold their breath as long afterward.
Each kid was encouraged to develop his own technique for this. I like this one.
Finally we measured lung capacity by doing water displacement. The competitive swimmer had the best lung volume.
Then we brought in pizza. It was a pleasant day and the kids could eat on the porch. The teens jammed in the basement. Yakov was home and always wants to take any opportunity to play with the lab drummer. PRM