Take a Breath

What's this Science Bite about?

Make your very own model lung! See it inflate and deflate as it "breathes" in this fun science activity.

Always remember to ask your parent or guardian to help you.

What you'll need

The items needed to make a model lung.

  • An empty 500ml drink bottle (clear, without sport cap)
  • Drinking straw
  • Balloon
  • Water Balloon (or another normal size balloon)
  • Scissors
  • Tape
  • Small piece of blu-tac or plasticine

How to do this experiment

Follow the instructions in the video below.

Can't see the video above? Watch it on Youtube.

  1. Rinse out your bottle with clean water and remove the label. With help from an adult cut off the bottom 1/4 to 1/3 of your bottle. Ask your adult to make a hole in the centre of the lid. This can be done in a couple of ways either by being very careful with a pair of sharp scissors, or by using a drill.
    A plastic bottle and a lid with a hole in it.

  2. Carefully tape the water balloon over one end of the straw and try to make sure that no air can escape between them. Feed the straw through the lid of the bottle and screw the lid on. It is also a good idea to put some blutac or plasticine around the hole where the straw goes in to make a seal. Now cut off the top of your other balloon and discard the top part.
    A bottle with a straw through the lid

  3. Now you need to stretch your balloon over the bottom of your bottle tightly. For this you might need someone to help you by holding the bottle. Once the balloon is stretched tightly, tape it in place sealing the edge.
    A complete model lung model
    Your model lung is now complete!

  4. To see your model lung work you need to pull down on the balloon at the bottom and if you watch the water balloon you can see it inflate. If you let go of the balloon or push it back in you can see it deflate.
    Pulling the balloon representing the diaphragm on the model lung

Find out more.

As we all know, we need our lungs for breathing, and we need oxygen from the air we breathe to allow our bodies to work and for us to stay alive.

There are many muscles that assist with breathing but the largest and most efficient is the diaphragm. This is a sheet of muscle that lies underneath the lungs.

When the diaphragm contracts it moves down creating move space inside the rib cage and pulling air into the lungs. This is called inhalation.

The diaphragm will then relax and move up, pushing air out of the lungs. This is exhalation.

We get a hiccup when the diaphragm suddenly contracts


A slightly more advanced model involves taping two straws together and using two balloons inside your model to show the air flowing into both of your lungs.

Curriculum Links

Body Systems and Cells

SCN 1-12a/ 2-12a/ 3-12a/ 4-12a

Physical Well Being

HWB 1-15a/ 2-15a/ 3-15a


Glasgow Science Centre