Science activity: how to make your own lung model with balloon

SCMP

3 Aug, 2022

Listen Now

Enjoy the audio version of this article!

Let's learn how to make a working lung!

You will need:

2 balloons
Empty bottle and cap
Straw
Scissors
Box cutter
Screwdriver
Blu-tack
Tape
An adult to help
Photo: Handout

Directions:

Step 1: Using a cutter, ask an adult to help you cut off the bottom of the bottle.

Step 2: Take one of your balloons, and tie the end in a knot.

Step 3: Use scissors to cut off the other end (not the tied end) of the balloon.

Step 4: Stretch the end of the balloon over the bottom of the bottle, and fix it there with tape.

Step 5: Ask an adult to help you drill a hole in the centre of the bottle with a screwdriver.

Step 6: Cut off the lip of the second balloon.

Step 7: Push the straw into the end of the untied balloon, fix it with tape, then push the straw through the bottom of the cap.

Step 8: Put the balloon-covered end of the straw into the bottle, and screw on the cap.

Step 9: Use some blu-tack to make a seal around the straw.

Step 10: Pull on the end of the balloon that is wrapped around the bottom of the bottle. The balloon inflates. When you push the bottom balloon up, the balloon inside deflates!

How it works

When the bottle is sealed by the balloon on one end, and the cap, straw and balloon at the other end, it is nearly airtight. This means air cannot go in or out.

When you pull the balloon, the volume of the container increases. However, the volume of air inside the container stays the same. This makes an area of low air pressure inside the bottle, while the air pressure outside the bottle stays the same. The higher air pressure from outside the bottle forces itself into the straw. Outside air rushes in to fill the straw and the balloon until the air pressure has balanced out.

Releasing the balloon brings the container back to its original air pressure, and the balloon deflates as air goes out of the straw.

Listen Now

Enjoy the audio version of this article!