It’s much more interesting and informative to do hands-on exploration than it is to read a dry textbook comparison of alveoli to air balloons. Monday morning my kids got to see how lungs work.
Believe it or not, these lungs are the same size! The only difference is that the lungs on the left have a little air in them; the lungs on the right are deflated.
We shoved a shop-vac hose down the trachea, then turned on the blower. It’s necessary to firmly hold the hose in place, otherwise the air pressure will dislodge the hose:
Even a small cut in a lung can inhibit breathing. The air goes out the hole instead of inflating the lungs:
Side-by-side with empty lungs and inflated lungs. Lungs hold a lot of air!
If you know anyone who raises beef, ask them to save the lungs for you when they butcher. This is well worth doing for a one-time experiment.
After the inflation experiment is done, give the kids a knife and let them cut into the sample. Let them feel the lungs and pop the alveoli like they would pop the bubble-wrap that comes in packages.
When you’re done, disinfect everything with plenty of bleach.