Gases in Air
Learning Objectives
Students will be able to:
- Name the main gases in air (nitrogen, oxygen, carbon dioxide)
- Explain that air is a mixture of different gases
- Create a model showing how much of each gas is in air
- Understand that we breathe in oxygen and breathe out carbon dioxide
The Big Question
"If air is real, what is it made of?"
Materials Needed
For the Class
- 100 small objects (beads, counters, or candies)
- 3 different colors needed
- Clear jar or container
- Chart paper
For Each Student
- Science notebook
- Colored pencils (blue, green, other)
- Air composition worksheet
- 10x10 grid paper
What's Air Made Of?
Air is a mixture of different invisible gases. Here's what's in every breath you take:
| Gas | How Much? | What Does It Do? |
|---|---|---|
| Nitrogen | 78 out of 100 parts | It's just there! We breathe it in and out without using it. |
| Oxygen | 21 out of 100 parts | This is what our bodies need! We use it to get energy from food. |
| Other gases | 1 out of 100 parts | Includes argon, carbon dioxide (CO2), and tiny amounts of other gases. |
Surprising Fact!
What Many People Think
"Air is mostly oxygen because that's what we need to breathe."
The Surprising Truth
Air is actually mostly NITROGEN! Almost 4 out of every 5 parts of air is nitrogen.
Activity: Build an Air Model (20 minutes)
Using 100 Objects to Show Air
If we had 100 tiny pieces of air, here's how many of each gas there would be:
- Get 78 blue objects - These represent NITROGEN
- Get 21 green objects - These represent OXYGEN
- Get 1 yellow/other object - This represents ALL OTHER GASES (including CO2!)
- Mix them all together in a clear jar
- Look at how much nitrogen there is compared to oxygen!
100 Grid Activity
Students can also color a 10x10 grid (100 squares):
- Color 78 squares BLUE for nitrogen
- Color 21 squares GREEN for oxygen
- Color 1 square YELLOW for other gases
What About Carbon Dioxide (CO2)?
Fun Fact: Carbon dioxide is a very important gas, but there's very little of it in air - only about 4 out of every 10,000 parts!
That's like having 4 special candies mixed into a bag of 10,000 regular candies. It's hard to find, but it matters a lot!
The Breathing Cycle:
Breathe In
We take in oxygen (O2) from the air
Body Uses It
Our body uses oxygen to get energy from food
Breathe Out
We breathe out carbon dioxide (CO2)
Think About It!
Discussion Questions:
- Why do you think plants need CO2 but we need oxygen?
- What happens to the air in a room when lots of people are breathing?
- If you were in a sealed room for a long time, what might happen to the air?
Science Notebook Activity (10 minutes)
Draw and label:
- Draw a circle representing air
- Divide it into sections showing:
- Nitrogen (biggest section - about 3/4)
- Oxygen (smaller section - about 1/4)
- Other gases (tiny sliver)
- Label each section
- Write: "The gas we need to breathe is ________"
- Write: "The gas we breathe out is ________"
Key Takeaways
- Air is a MIXTURE of different gases
- Most of the air is nitrogen (78 out of 100 parts)
- Oxygen is the gas we need to breathe (21 out of 100 parts)
- Carbon dioxide (CO2) is a tiny part of air, but it's important
- We breathe in oxygen and breathe out CO2
Vocabulary Words
Nitrogen
The most common gas in air. We breathe it in and out but don't use it.
Oxygen
The gas our bodies need. We use it to get energy from food.
Carbon Dioxide (CO2)
A gas we breathe out. Plants use it to make food!
Gas
A form of matter that spreads out to fill any space. Air is made of gases.