This neat visual of how a lung and diaphragm work together can be made with just a few simple household items. It was a great dose of STEM learning on a stormy day cooped up inside.
You’ll need to start with a sturdy plastic bottle. At first I assumed larger was better, and tried a family-sized club soda bottle… but our balloon wouldn’t fit in the next step, so be aware! You really need a single-serving bottle (16 ounces), either of water or soda.
Carefully cut the bottle in half. This was definitely a grown-up step, and I cautioned Travis that the edge of the bottle was a bit jagged. Keep the top half; recycle the bottom of the bottle.
Tie a knot in an uninflated balloon, and snip off the top of it. Stretch that top over the end of the bottle, and secure with a rubber band.
Your bottle might squash a bit, but that’s fine as long as no air can get in.
Now slide a straw into a second balloon. Secure them together with a rubber band, making sure the balloon is attached, but not so tight that air can’t get in. Travis tested with a few huffs!
Now push the balloon into the neck of the bottle, and use a little clay around the straw to hold it in place.
Holding the bottle firmly, pull down on the bottom balloon. The balloon inside will inflate!
Explain to kids that this movement replicates what happens when you breathe: when your diaphragm moves down with each breath in, it makes room for your lungs, which then fill with air.
Travis’s favorite part of the activity was trying to get the balloon to “hiccup”, which you can do by pulling the bottom balloon a few times quickly. The balloon in the bottle will jump, which is what happens when you get a case of the hics.