Breathe easy: Monitor and reduce carbon dioxide in the classroom
Before the lesson, you'll need to ...
Worksheet: CO2 in enclosed spaces
Syllabus content
New NSW Syllabus:
Science and Technology
- ST3-PQU-01: Poses questions to identify variables and conducts fair tests to gather data.
- ST3-DAT-01: Interprets data to support explanations and arguments.
- ST3-PQU-01: Poses questions to identify variables and conducts fair tests to gather data.
- ST3-DAT-01: Interprets data to support explanations and arguments.
PDHPE
- PH3-IHW-01: Examines and explains factors that influence identity, health, and wellbeing of individuals and groups.
- PH3-SMI-01: Evaluates and applies self-management and interpersonal skills in a range of contexts.
- PH3-IHW-01: Examines and explains factors that influence identity, health, and wellbeing of individuals and groups.
- PH3-SMI-01: Evaluates and applies self-management and interpersonal skills in a range of contexts.
Mathematics
- MAO-WM-01: Working mathematically through real-world data collection and analysis.
- MA3-DATA-01: Constructs graphs using many-to-one scales.
- MA3-DATA-02: Interprets data displays, including line graphs.
- MAO-WM-01: Working mathematically through real-world data collection and analysis.
- MA3-DATA-01: Constructs graphs using many-to-one scales.
- MA3-DATA-02: Interprets data displays, including line graphs.
Current NSW Syllabus:
Science and Technology
- ST3-1WS-S: Plans and conducts scientific investigations to answer questions, including fair testing.
- ST3-2DP-T: Plans and uses materials, tools, and equipment to develop solutions for a need or opportunity.
- ST3-11PW-ST: Explains how energy can be transformed from one form to another.
- ST3-1WS-S: Plans and conducts scientific investigations to answer questions, including fair testing.
- ST3-2DP-T: Plans and uses materials, tools, and equipment to develop solutions for a need or opportunity.
- ST3-11PW-ST: Explains how energy can be transformed from one form to another.
PDHPE
- PD3-7: Proposes and implements actions and protective strategies that promote health, safety, wellbeing and physically active spaces.
- PD3-7: Proposes and implements actions and protective strategies that promote health, safety, wellbeing and physically active spaces.
Mathematics
- MAO-WM-01: Working mathematically through real-world data collection and analysis.
- MA3-DATA-01: Constructs graphs using many-to-one scales.
- MA3-DATA-02: Interprets data displays, including line graphs.
- MAO-WM-01: Working mathematically through real-world data collection and analysis.
- MA3-DATA-01: Constructs graphs using many-to-one scales.
- MA3-DATA-02: Interprets data displays, including line graphs.
Assessment
Teacher background information
Carbon dioxide (CO2)
Although students don’t need a detailed understanding of carbon dioxide at stage 3, it does help them develop a greater understanding of concepts throughout this program.
Carbon dioxide (CO2) is a naturally occurring colourless and odourless gas. It plays an essential role in Earth’s carbon cycle and environmental processes. Carbon dioxide gas is slightly denser than air, which allows it to accumulate in low-lying or enclosed spaces, such as basements, poorly ventilated classrooms or vehicles.
Although students don’t need a detailed understanding of carbon dioxide at stage 3, it does help them develop a greater understanding of concepts throughout this program.
Carbon dioxide (CO2) is a naturally occurring colourless and odourless gas. It plays an essential role in Earth’s carbon cycle and environmental processes. Carbon dioxide gas is slightly denser than air, which allows it to accumulate in low-lying or enclosed spaces, such as basements, poorly ventilated classrooms or vehicles.
Natural role of CO2
Carbon dioxide is a critical component of photosynthesis, the process by which plants absorb CO2 and sunlight to produce glucose and oxygen, essential for life on Earth. Carbon dioxide is also released through respiration in animals and humans and during natural processes such as volcanic eruptions and decomposition of organic matter.
Carbon dioxide is a critical component of photosynthesis, the process by which plants absorb CO2 and sunlight to produce glucose and oxygen, essential for life on Earth. Carbon dioxide is also released through respiration in animals and humans and during natural processes such as volcanic eruptions and decomposition of organic matter.
Human activities and CO2
Human activities, especially burning fossil fuels like coal, oil and natural gas, have significantly increased CO2 levels in the atmosphere. This contributes to the greenhouse effect, which traps heat in the Earth’s atmosphere, leading to global warming and climate change. In addition, CO2 is a common indoor air pollutant in confined spaces, a result of human respiration and insufficient ventilation.
Human activities, especially burning fossil fuels like coal, oil and natural gas, have significantly increased CO2 levels in the atmosphere. This contributes to the greenhouse effect, which traps heat in the Earth’s atmosphere, leading to global warming and climate change. In addition, CO2 is a common indoor air pollutant in confined spaces, a result of human respiration and insufficient ventilation.
CO2 and health
Although CO2 is not toxic at normal outdoor levels, elevated concentrations in enclosed spaces can cause health issues such as fatigue, headaches and difficulty concentrating. This is why it's essential to monitor CO2 and, if needed, improve ventilation in classrooms or other environments with multiple occupants.
Although CO2 is not toxic at normal outdoor levels, elevated concentrations in enclosed spaces can cause health issues such as fatigue, headaches and difficulty concentrating. This is why it's essential to monitor CO2 and, if needed, improve ventilation in classrooms or other environments with multiple occupants.
Properties of CO2
Density: CO2 is denser than air, which is why it sinks and can accumulate in low areas.
Solubility: CO2 dissolves in water to form carbonic acid, lowering pH. This property explains its use in carbonated beverages and its role in acidification of natural water sources.
Density: CO2 is denser than air, which is why it sinks and can accumulate in low areas.
Solubility: CO2 dissolves in water to form carbonic acid, lowering pH. This property explains its use in carbonated beverages and its role in acidification of natural water sources.
Carbon cycle
Although the carbon cycle is not explained in this program, understanding it may help you to answer student questions that arise. A natural process, it recycles carbon through Earth’s atmosphere, oceans, soil and living organisms, maintaining a balance essential for life. Carbon dioxide in the atmosphere is absorbed by plants during photosynthesis to create energy and oxygen. Animals, including humans, consume these plants and release CO2 back into the atmosphere through respiration. When plants and animals die, they decompose, returning carbon to the soil or forming fossil fuels over millions of years.
Bushfires play a significant role in the carbon cycle by rapidly releasing large amounts of stored carbon from vegetation back into the atmosphere as CO2. This carbon is typically reabsorbed from the atmosphere over time as ecosystems regenerate. However, increased frequency and intensity of bushfires linked to human activity and climate change, can lead to higher levels of atmospheric CO2, disrupting the cycle. The carbon cycle, including the role of bushfires, highlights the interconnectedness of life and importance of sustainability and climate action.
For more age-appropriate information about CO2 and carbon, visit: NASA. (n.d.). Carbon.
Although the carbon cycle is not explained in this program, understanding it may help you to answer student questions that arise. A natural process, it recycles carbon through Earth’s atmosphere, oceans, soil and living organisms, maintaining a balance essential for life. Carbon dioxide in the atmosphere is absorbed by plants during photosynthesis to create energy and oxygen. Animals, including humans, consume these plants and release CO2 back into the atmosphere through respiration. When plants and animals die, they decompose, returning carbon to the soil or forming fossil fuels over millions of years.
Bushfires play a significant role in the carbon cycle by rapidly releasing large amounts of stored carbon from vegetation back into the atmosphere as CO2. This carbon is typically reabsorbed from the atmosphere over time as ecosystems regenerate. However, increased frequency and intensity of bushfires linked to human activity and climate change, can lead to higher levels of atmospheric CO2, disrupting the cycle. The carbon cycle, including the role of bushfires, highlights the interconnectedness of life and importance of sustainability and climate action.
For more age-appropriate information about CO2 and carbon, visit: NASA. (n.d.). Carbon.
Fair test
In science, a fair test ensures an experiment is conducted such that only 1 variable is changed at a time, keeping all other conditions constant. This allows students to clearly identify cause-and-effect relationships. For example, in the CO2 balloon experiment of this lesson, the variable tested is the type of gas inside the balloon, with all other factors (balloon size, height of drop) kept constant. Fair tests teach students critical thinking and the importance of experimental reliability.
In science, a fair test ensures an experiment is conducted such that only 1 variable is changed at a time, keeping all other conditions constant. This allows students to clearly identify cause-and-effect relationships. For example, in the CO2 balloon experiment of this lesson, the variable tested is the type of gas inside the balloon, with all other factors (balloon size, height of drop) kept constant. Fair tests teach students critical thinking and the importance of experimental reliability.
Independent variable
The independent variable is the variable that is intentionally changed in an experiment to test its effect on the outcome, sometimes called the 'manipulated variable'. For example, in this lesson's balloon experiment, the independent variable is type of gas inside the balloons (such as CO2, exhaled air or normal air). Changing this variable allows students to observe differences in how the balloons fall. Understanding independent variables helps students grasp the concept of experimental design. It's an essential skill outlined in the NSW syllabus, which encourages students to pose questions and test variables in investigations.
The independent variable is the variable that is intentionally changed in an experiment to test its effect on the outcome, sometimes called the 'manipulated variable'. For example, in this lesson's balloon experiment, the independent variable is type of gas inside the balloons (such as CO2, exhaled air or normal air). Changing this variable allows students to observe differences in how the balloons fall. Understanding independent variables helps students grasp the concept of experimental design. It's an essential skill outlined in the NSW syllabus, which encourages students to pose questions and test variables in investigations.
Dependent variable
The dependent variable is what's measured or observed in an experiment. It shows the effect of changing the independent variable. In this lesson's balloon experiment, the dependent variable is how quickly the balloon falls, which depends on the type of gas inside. Students record observations or numerical data related to this variable, helping them analyse cause-and-effect relationships. Measuring and analysing dependent variables teaches students how to draw conclusions based on evidence.
The dependent variable is what's measured or observed in an experiment. It shows the effect of changing the independent variable. In this lesson's balloon experiment, the dependent variable is how quickly the balloon falls, which depends on the type of gas inside. Students record observations or numerical data related to this variable, helping them analyse cause-and-effect relationships. Measuring and analysing dependent variables teaches students how to draw conclusions based on evidence.
Controlled variable
Controlled variables are the conditions kept constant during an experiment to ensure a fair test. For example, in this lesson's balloon experiment, controlled variables are balloon size and height from which balloons are dropped. Keeping these variables consistent ensures any differences in how the balloons fall are solely due to the independent variable (gas inside). Teaching students about controlled variables emphasises the importance of eliminating bias and improving experimental accuracy.
For more information on fair tests, independent, dependent and controlled variables, and how they relate to the science syllabus, visit:
New South Wales Department of Education. (2025). Science and technology K-6: Teaching and learning.
Controlled variables are the conditions kept constant during an experiment to ensure a fair test. For example, in this lesson's balloon experiment, controlled variables are balloon size and height from which balloons are dropped. Keeping these variables consistent ensures any differences in how the balloons fall are solely due to the independent variable (gas inside). Teaching students about controlled variables emphasises the importance of eliminating bias and improving experimental accuracy.
For more information on fair tests, independent, dependent and controlled variables, and how they relate to the science syllabus, visit:
New South Wales Department of Education. (2025). Science and technology K-6: Teaching and learning.
Lesson content
Slide presentation part 1: Introduction
Slide presentation part 2: CO2 in enclosed spaces
Worksheet: CO2 in enclosed spaces
Slide presentation part 3: CO2 in our classroom
Extension Opportunities
Extension of experiment
Have students change 1 variable to change the experiment. For example, how does the number of people in the room impact CO2 levels? What about changes to activity levels? Or ventilation? Remember, change just 1 of these variables at a time, keeping all other variables the same.
Have students change 1 variable to change the experiment. For example, how does the number of people in the room impact CO2 levels? What about changes to activity levels? Or ventilation? Remember, change just 1 of these variables at a time, keeping all other variables the same.
Research human health impacts of CO2
Assign small groups to research specific health impacts of elevated CO2 levels, such as fatigue, reduced concentration or respiratory issues.
Students create a mini-presentation or poster to summarise their findings.
Assign small groups to research specific health impacts of elevated CO2 levels, such as fatigue, reduced concentration or respiratory issues.
Students create a mini-presentation or poster to summarise their findings.
Design an awareness campaign
Have students design posters, infographics or videos to raise awareness about the importance of monitoring CO2 levels and improving air quality in their car, school or community.
Encourage students to communicate their learning creatively and advocate for environmental change. Students should include actionable tips in their work, such as, 'open windows regularly' or 'ride share to cut emissions'.
Have students design posters, infographics or videos to raise awareness about the importance of monitoring CO2 levels and improving air quality in their car, school or community.
Encourage students to communicate their learning creatively and advocate for environmental change. Students should include actionable tips in their work, such as, 'open windows regularly' or 'ride share to cut emissions'.
Explore global CO2 levels
Provide students with data on global CO2 emissions from different countries or regions. Use online resources like World Bank data.
Students analyse the data, identify patterns and discuss reasons why some countries have higher emissions than others.
Encourage students to discuss what actions individuals, communities, and governments can take to reduce CO2 emissions globally.
Provide students with data on global CO2 emissions from different countries or regions. Use online resources like World Bank data.
Students analyse the data, identify patterns and discuss reasons why some countries have higher emissions than others.
Encourage students to discuss what actions individuals, communities, and governments can take to reduce CO2 emissions globally.
Vocabulary
Learning journal prompts
What did I learn?
What are CO2 levels and why is it important to monitor them in a classroom?
What did you discover about how CO2 levels change in the classroom?
How does high CO2 impact our health and ability to focus?
What did today’s experiment teach you about fair testing and why it’s important?
What are CO2 levels and why is it important to monitor them in a classroom?
What did you discover about how CO2 levels change in the classroom?
How does high CO2 impact our health and ability to focus?
What did today’s experiment teach you about fair testing and why it’s important?
Connecting and acting
Why is ventilation important in classrooms or homes?
What actions can we take to reduce CO2 levels in our classroom or home?
How do strategies to reduce CO2 in the classroom apply to other indoor spaces like your home or car?
If you were designing a new classroom, what features would you include to manage CO2 levels effectively?
Why is ventilation important in classrooms or homes?
What actions can we take to reduce CO2 levels in our classroom or home?
How do strategies to reduce CO2 in the classroom apply to other indoor spaces like your home or car?
If you were designing a new classroom, what features would you include to manage CO2 levels effectively?
Personal reflections
What surprised you about today’s lesson?
Did this lesson change what you think about ventilation and air quality? Why or why not?
How did learning about CO2 levels in your classroom make you feel about the air you breathe indoors?
How do you feel knowing that you can take steps to improve the air quality in your classroom?
What surprised you about today’s lesson?
Did this lesson change what you think about ventilation and air quality? Why or why not?
How did learning about CO2 levels in your classroom make you feel about the air you breathe indoors?
How do you feel knowing that you can take steps to improve the air quality in your classroom?
Filter heroes: Assemble and test HEPA filters to improve air quality
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