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We’re continuing our study of the human body for Biology I and Life Science this year with our 5th, 8th, and 10th graders. We’re using CK-12 for our text both the Life Science and Biology with some other resources like The Way We Work. Today we will do an investigation- **Science Quest Measuring Lung Capacity**.

## Let’s Investigate Lung Capacity

Lung capacity refers to **the amount of air your lungs can hold**. There are a number of things that can affect your lung capacity, such as:

- your overall health
- specific health conditions- like asthma or emphysema
- athleticism- how active you are
- size
- age

This activity aims to determine your lung capacity and to make predictions about what can affect it. Talk about lung capacity and have your kids make a hypothesis about what things can change it- for the better or the worse. Then test your hypothesis!

## Measure Lung Capacity

The purpose of the investigation is to determine our own lung capacity and then depending on your student’s hypothesis do some additional testing and measure lung capacity again. You will need a balloon (the kind that blows up into a regular balloon shape, not the oblong sort), a measuring tape or ruler, and something to record data with and on. In general, the following procedure will get you started.

- Stretch your balloon.
- Take a deep breath and blow all at once into the balloon and close it off.
- Shape the balloon into a sphere shape while holding the air in.
- Ask a partner to measure the circumference of the balloon at the middle. (You could measure the diameter and for younger kids this might be best, but it’s less accurate)
- Record the number in centimeters.
- Repeat two more times.
- If your hypothesis indicates exercise, repeat after doing a set of exercises.

## Collect Data on Lung Capacity

The data you collect will depend on the hypothesis your students put forward. Originally, I instructed my kids to compare lung capacity with height, but they chose to investigate other possibilities. In the classroom, all students would do the same lab, but in a homeschool why not? We discussed how their ideas changed the way they’d go about it and we proceeded. At a minimum, you need to record:

- The
**circumference of the balloon**which you determine with the measuring tape. **Record all your measurements in centimeters**. The metric system is mathematical language of the science world. This is important for U.S. students!- The person’s name so you can match the data with the right person
- Age and height if you need them
- The diameter can be measured, but it’s easier to be accurate when measuring the circumference. However, I left room to write the diameter which will be calculated from the circumference.

## Calculate Lung Capacity

The bonus in this science lab is the math that kids get to do! You will be calculating two things in order to interpret the results.

**Determine the diameter of the sphere**from the circumference using the equation circumference = 2πr. Remember that r is half of the diameter and that we have measured circumference. So, circumference is πd and d= c/π.**Calculate the Volume of a Sphere**using the diameter to find the radius and then the equation below.

All of our kids from 5th to 10th grade were able to use these equations and ultimately calculate the volume of the balloon that they had blown into. **If the math is out of reach of your students, then you can simply use the diameter** to determine which is the largest and smallest balloon. I encourage you to challenge your student with the extra math.

## Drawing Conclusions about Lung Capacity

Now it’s time to look at your data and decide whether or not it supports your hypothesis. Did the numbers match what you thought would happen? Rather than answering a bunch of questions, a conclusion can simply be a statement. Feel free to discuss the results with your kids to help them form their thoughts. Include:

- A summary of the results
- How the date supports or refutes the hypothesis
- Reasons why you think the results came out the way they did
- How you would conduct the experiment differently if you were to repeat it
- Summary statement on the outcome based on the data you have interpreted

## Lab Sheet on Measuring Lung Capacity

To help you along, I thought I’d include a **lab sheet** with today’s Science Quest. My own kids jotted all this down on a piece of notebook paper (my favorite) and they made their own data chart. Making their own data charts helps kids and teens to learn how to organize information on their own which is an important skill. However, having the procedure written out already will make it easy to **print and go**!

## Other Science Quests at Blog, She Wrote

I’ve made it a goal this year to share more specific science activities with you. Here are a few more science labs and activities. More are on the way!

**How to Determine the Frequency of a Trait**– A lesson in the Hardy-Weinberg principle while reading about Mendel’s work. This is a wonderful lab for high school and middle school. Homeschool style.

**Observing Onion Cells**– A lesson in the observation of a cell and the use of microscopes.

**How to Make a Marble Speed Trap with LEGO Mindstorms**– An activity using the Mindstorms EV3 system to determine the speed of a marble on a track.