5. METHOD
1.
Blow up a balloon to about 20
cm in diameter two or three
times to stretch it. Release the
air each time.
2.
Take the biggest breath you
can, then blow out all the air
you can into the balloon. Tie
up the end of the balloon to
hold in your ‘blown out’ air.
3.
Use a ruler to measure the
diameter of the balloon as
shown:
6. METHOD
4. Use the table below to determine your approximate
lung capacity (labelled vital capacity) in litres.
5. Release the air from the balloon and repeat your
measurement of lung capacity three more times.
Average your results to get your best estimate of the
maximum ‘blow-out’ of your lungs.
8. DISCUSSION
1. Why were you asked to stretch the balloon first?
2. Why did you measure your lung capacity four
times?
3. Compare your measurements with others in your
class. Is there a lot of variation from person to
person?
4. Suggest another way of measuring the amount of
air exhaled with each breath.
