Interpret Data When Investigating Total Lung Capacity

Did you know that on average our lungs can hold around six litres of air?

That's about 25 cups of air!

The maximum amount of air we breathe in and out is called our total lung capacity. Our lung capacity can be affected by many factors like age, fitness and health. 

A larger total lung capacity means more oxygen is taken into the body with every breath. Through exercise, athletes can increase their vital lung capacity. This allows athletes to perform better! Measuring our lung capacity can also help identify any potential problems with our lungs.

So how do we measure lung capacity? 

Lung capacity can be measured fairly easily. Here's what's needed and what you have to do: 

Equipment: 

- plastic or rubber tubing/straw

- large plastic bottle/container

- tank or bucket of water

- measuring cylinder

- permanent marker pen

Method:

1. Fill the tank/bucket with water

2. Measure 100 ml of water using the measuring cylinder

3. Pour the water from the measuring cylinder into the plastic container/bottle

4. Mark where the water comes up to on the plastic bottle with a permanent pen 

5. Continue to fill up the plastic container/bottle with water 100 ml at a time until you get to the very top

6. Put the rubber tubing into the bottle 

7. Turn the plastic container/bottle upside down in the tank keeping the bottle neck submerged in the water 

8. Take a deep breath and breathe out into the rubber tubing in one breath

9. Count the lines above the water line and multiply by 100, this is your lung capacity

10. Record your lung capacity and repeat two more times (so three times in total) and calculate an average

When we breathe out fully, the air in our lungs will replace the water in the bottle, giving us our total lung capacity.

The reason why we repeat our measurements in an experiment is so we get more data. We can compare the measurements and see how similar they are to one another or if there's a pattern. We can also use these measurements to spot any anomalous results, which are the ones that are very different (odd) or don't follow a pattern.

Here is some data showing the total lung capacity of a student: 

An average is calculated by adding all three trials and then dividing the sum by the number of trials (3): 

200 + 190 + 200 = 590 

590 ÷ 3 = 196.6

Here is some more data:

Did you spot the anomalous result? 

Trial 4 had a measurement that was very different to the other trials. In this case, we can leave this measurement out when calculating our average: 

200 + 190 + 200 + 195 = 785

785 ÷ 4 = 196.2

We divided by 4 because we only used 4 measurements. 

The more we repeat our measurements, the more likely the mean is to be close to the real value.

In this activity, we're going to interpret data when investigating total lung capacity.

Are you ready?