Page 19 - 新思维科学学生用书8 样章

1 Respiration

How much air can you breathe out?

Think like a scientist

Measuring the volume of air you can push out of your lungs
How much air do you think you can push out of your lungs in one breath?
In this experiment, you will use some very simple apparatus to find out.

You will need:
• big plastic bottle with a lid • measuring cylinder • bendy tubing

• marker pen • water • big bowl

Safety
The bottle and bendy tubing must be clean, and the water you use must be safe to

drink. Do not share the mouthpiece with anyone else or put it on the work surface
when you have finished.

You may get water on the floor as you do your experiment. Take care not to slip in it.

Method
1 You are going to use the plastic bottle to measure volumes.
In your group of three, discuss how you can use the measuring cylinder to mark
a scale on the plastic bottle.

Then mark the scale on the bottle. The scale should go all the way from the
bottom to the top of the bottle.
2 Fill the bottle right to the top with water. Put the lid on.

3 Pour water into the big bowl until it is about half
full. Turn the bottle upside down, and hold it in the
bowl. Very carefully take the lid off the bottle. You
should find that all the water stays in the bottle.
4 Carefully slide the bendy tubing into the top of the

bottle, under water.
5 Take a deep breath in, then put your mouth over
the tubing and breathe out as much air as you can

through the tubing. Your expired air will push out
some water from the bottle.
Use the scale that you drew on the bottle to record the volume of air you
breathed out.

18