What it shows
Our lungs hold air. We can compare how much air different people can blow out in one breath by measuring a balloon.
The science
When we breathe in, our lungs fill with air, and when we breathe out the air leaves. A bigger person or someone with practice usually has a bigger lung capacity. A balloon grows as air is blown in, so the size around it shows how much air we blew in one breath.
Materials
Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Three balloons of the same type (under Rs 50)
- A tape measure or a piece of string and a ruler
- Paper and pencil
- A friend and a parent to compare
Safety
For this project: An adult must help children who feel dizzy. Stop if you feel faint. Do not share the same balloon. Keep balloons away from babies.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Stretch a balloon a few times before blowing.
Take a deep breath in through your nose.
Blow out into the balloon in one go, as much as you can.
Pinch the neck of the balloon with your fingers so air does not escape.
Wrap the string around the fattest part of the balloon.
Measure the string against the ruler and write the number.
Let your friend and a parent do the same with their own balloons.
Make a bar chart to compare the three.
What you should see
An adult’s balloon is usually bigger than a child’s. Each person gets a measure of their own breath.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What fills the balloon?
Air from our lungs.
2Which organ holds air?
The lungs.
3Why did we use the same type of balloon?
To make it a fair test.
4Who blew the biggest breath?
Read from your chart.
Take it further
Measure before and after a run and see whether your breath changes.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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