Teacher Preparation

Overarching learning goal: By participating in this activity students recognise the role of CO₂ in respiration and photosynthesis. Students will observe the effects of photosynthesis and respiration of plants and will understand the role of plants in the carbon cycle.

Teacher content information: For information on the role of plants in the carbon cycle and the relationship between plants and global warming, see the information below -

NASA - The Carbon Cycle

Video: NASA - Global Warming Reduces Plant Productivity - http://youtu.be/Er3iD5PIR00

NOTE: This video is on Youtube. Some schools have disabled access to Youtube. If you want students to see this video, you may need to ask them to watch it at home prior to conducting this activity.

For more reliable information about climate change in Australia, visit the Climate Council.

The IPCC

The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. It was created to:

provide policymakers (governments) with regular scientific updates about climate change;
highlight the impact climate change will have on the planet in the future; and,
offer some ideas about how to tackle the challenges of climate change's potential effects on the planet.

In 2021-22, the IPCC released their sixth assessment report. This is the most up-to-date physical understanding of the climate system and climate change.

The report makes a number of important points:

It is unequivocal that human influence has warmed the atmosphere, ocean and land.
Global surface temperature will continue to increase until at least mid-century under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades (B1). The report describes five possible climate futures, where #1 is not great and #5 is extremely bad. If we want to keep global warming at less than two degrees, which the IPCC says is the best-case scenario, we need to reduce our CO2 and greenhouse gas emissions significantly and start right away.

'Net zero' or 'carbon neutral' are terms that refer to achieving an overall balance between greenhouse gas emissions produced and greenhouse gas emissions taken out of the atmosphere. Getting to net zero means we can still produce some emissions, so long as we're doing something else to reduce the greenhouse gases already in the atmosphere at the same time, kind of like balancing a set of scales (more info).

Psychological safety. The IPCC Report sets a hard challenge. While this real-world issue is essential for students to understand, there is no doubt it can make them feel sad or anxious about the future is becoming darker and scarier by the day. So, reassure students that we can have a hopeful and optimistic outlook on this report, rather than one of doom and gloom. Explain that optimism involves looking objectively at a situation and making a conscious decision to focus on the good (more info), and that hope is the belief that you can make an impact (more info). Explain to students that you are going to look ahead, identify what needs to be improved, and then work on the skills and confidence so that they can go out and do it. If you're interested in learning more about how to approach challenging topics around climate change and sustainability in your classroom through a Hope and Optimism lens, consider our PD course.

Students can conduct this experiment in groups over two days, or you can prepare one example for the class prior to conducting sharing this experiment with students.

Student and classroom organisation

Preparation: You will probably want to prepare this experiment a day in advance, so that students can observe the results immediately. Alternatively conduct this activity over two days.

For both of the experiments students are asked to complete the Predict, Observe, Explain thinking tool using the prompts on the Student Worksheet.

Predict – Before commencing the experiment, students should commit to a prediction and record their prediction.
Observe – Students should then observe the experiment and record what they see.
Explain – Students should explain the ways in which their prediction matched the results and why.

Experiment 1. Testing for carbon dioxide produced by plants during respiration

In this experiment you will be testing for CO₂ produced by plants in respiration. During the day, plants use sunlight and water to create their own energy – so what do they do at night or in the absence of sunlight?

Students can conduct this experiment in groups over two days, or you can prepare one example for the class prior to conducting sharing this experiment with students.

For this experiment you will need:

Small leafy plant
Large jar with lid (big enough to contain the plant)
Small container with lime water

Steps for conducting experiment:

Place the plant inside the jar.
Fill the small container with lime water and place it inside the jar.
Close the jar and store it in a dark place overnight.

Experiment 2. Testing for carbon dioxide produced by people when exhaling.

We exhale approximately 200ml of CO₂ every minute – and a mixture of other gases depending on what we have inhaled.

In this experiment you will be asking students to breathe through a straw into some lime-water. It will take a while for a reaction to occur.

For this experiment you will need:

Cup of lime-water
Straw
Student volunteer

Steps for conducting experiment:

Fill cup with lime-water.
Ask student volunteer to breathe through a straw into the lime-water. It will take a while for a reaction to occur.

Reflection - The importance of plants

Working in pairs or small groups ask students to create an infographic describing the role of plants in the carbon cycle, including information about what would happen if all the plants and algae were removed overnight. DIY infographic information.

Homework/Extension

1. Ask students to create a CO₂ graffiti wall using the Graffiter website create a graffiti wall based on what they have learnt about plants and CO₂. Students should choose a wall, create a message and download their image as a JPG to share with the class.

2. Students can think of other ways to demonstrate the emission of carbon dioxide. How could this form of experiment be used to demonstrate personal carbon dioxide emissions?

Weather Makers - The role of plants in managing CO2

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