You will need:
- A clean dry plastic bottle (around 600mL works well but other sizes are OK too)
- Two balloons
- A straw
- Scissors
- Sticky tape, masking tape or electrical tape
- A rubber band
- Blu-tack, modelling clay, plasticine or firm playdough
Carefully cut the bottom off the plastic bottle and cut the top (the rounded part) off one of the balloons.
Stretch the cut part of the balloon over the bottom of the bottle so it forms a thin skin like the surface of a drum, with the neck of the balloon hanging free. Secure with tape. This balloon represents the diaphragm.
Put the straw inside the other balloon and attach them using the rubber band. Be careful to make it tight enough that it won’t slip off but not too tight to crush the straw (you need air to flow through).
Put the balloon inside the bottle. It should be hanging free and not touching the other balloon. This hanging balloon represents the lung.
Hold the straw in place using the blu-tack (or other modelling material) to create a lid. Ensure the entire neck of the bottle is covered to make an air-tight seal.
Your lung model is ready to use!
Carefully pull the balloon at the base of the bottle up and down and watch as the other balloon inflates. This represents the action of the diaphragm and the inflation of the lungs.
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Why Does This Happen?
When you breathe in, your diaphragm – the muscle at the base of your lungs, contracts. This expands your chest cavity, lowering the air pressure of the cavity below the air pressure outside, and inflating the lungs.
You can see this same principle at work in this ‘homemade lung’. When you pull on the diaphragm balloon, it lowers the air pressure in the bottle. This pulls in air from outside the bottle, allowing the balloon at the top – the lung – to inflate.
Variables to test
- Change the size of the balloons.
- Change the size of the bottle.
- Can you make this work with more than one balloon as a “lung”
Teaching about the human body? From 5 senses to the skeletal system, the Human Body workshop has you covered!
Get in touch with FizzicsEd to find out how we can work with your class.
Human Body
Years 3 to 6
Maximum 30 students
School workshop (NSW only)
60 or 90 minutes
Online Class Available
Liquid Nitrogen Show
Years 7 to 10
Maximum 60 students
Science show
45 minutes
Online Class Available
STEM Full Day Accelerator - Primary
Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials.
wow thats so cool
Glad you liked it!