What You Need:
- One-liter plastic bottle with cap
- Drinking straw
- Duct tape
- Two rubber bands
- Two regular balloons
What You Do:
- These first couple of steps should be carried out by an adult, as cutting plastic can be dangerous. To begin, gouge a ⅜ inch hole in the center of the bottle cap.
- Cut the bottom of the bottle off. It helps to make an initial gouge before cutting the plastic.
- Have your child make sure that both the cap and the bottom of the bottle have no rough edges.
- Next, let him use the scissors to cut the neck off one of the balloons.
- Help your child stretch the “neckless” balloon over the open bottom of the bottle
- Have him secure the stretched balloon to the bottle with a rubber band.
- Let him place the straw inside the neck of the other balloon.
- Help him push the balloon—with the straw still inside—through the hole he made in the bottle cap. The balloon neck should be on top. Leave about an inch of the balloon above the bottle hole.
- Have your child screw the cap on the bottle.
- Secure the balloon around the straw with a rubber band.
- Let your child block any remaining opening in the top of the bottle with duct tape.
- Now it's time for your child to make his model lung “breathe." Have him hold the middle of bottle with one hand while he gently tugs the cut balloon out of the bottom of the bottle. The cut balloon represents the diaphragm, the muscle that allows air to move in and out of the lungs.
- When your child tugs the cut balloon, he creates more space inside the lung's respiratory cavity. Air will move in, puffing up the balloon at the top. This represents what happens when a human breathes in.
- Now have your child push the cut balloon back inside the bottle. The balloon at the top should deflate. This action represents what happens when a human breathes out.
Once your child gets the hang of making his model breathe, have him try closing his eyes and putting his ear near the straw as you move the cut balloon diaphragm back and forth. He should hear his model lung “breathing.” He can also use his model to investigate a few respiratory system disorders. If he tugs randomly at several places of the cut balloon, he can simulate a cough, which is caused by spasms in the diaphragm. By partially blocking the straw, your child can see the results of the narrowing of the respiratory tubes as seen in patients with asthma.