Balloon Lung

What you need:

• Clear disposable plastic cup

• 1 straw

• 2 rubber bands

• Tape

• 2 balloons

• Scissors

What you do:

1. Use scissors to poke a hole in the center of the bottom of your plastic cup, big enough to the straw to fit into. Just don't put the straw in yet.

2. Cut your straw in half.

3. Take one balloon and cut the tip of the neck off—but not the whole "neck" of the balloon.

4. Take your second balloon and tie a knot at the "neck." Then, cut off the wider, main part of the balloon.

5. Put the straw into the first balloon through the neck and seal the straw and the balloon together with tape.

6. Take the straw and push it through the opening of the cup and into the hole. Push the straw through the hole so that it sticks up outside of the cup.

7. Take the second balloon—with the knot—and stretch it over the open end of the cup.

   1. Use your second rubber band or add tape around the edges to secure the balloon around the cup.

8. Hold the cup up and pull the knot on the bottom balloon to see your lungs in motion.

Questions to ask:

1. What happens when you pull down on the balloon? What happens when you release it?

2. What organs do the different parts of the model represent?

What's the science:

You created a model of the human respiratory system, which works to bring oxygen into the body and expel carbon dioxide from the body. In this model, the cup represents your rib cage, the straw your trachea, the first balloon your lung and the second balloon as your diaphragm.

Your diaphragm is an important muscle located below your lungs that makes it possible for you to breathe. When your diaphragm moves down, it creates more room in your chest, allowing your lungs to inflate as you breathe in. When your diaphragm moves up, it creates less room in your chest, causing your lungs to deflate as you breathe out.