Sue Johnson from the Institute of Education, London University, UK, introduces the Plant Scientists Investigate project, and presents three plant-related activities for primary-school children. Compare the carbon dioxide concentrations of inhaled and exhaled air, visualise your own oxygen…
Plant Scientists Investigate: at school and in the botanic garden
The Plant Scientists Investigate project promoted collaboration between botanic gardens and local primary schools between 2005 and 2007. From Austria, Bulgaria, Italy and the UK, primary-school teachers, head teachers, representatives of national school boards (county advisors in the UK) as well as botanic garden educators have worked together to develop an enquiry-centred teaching resource.
Key features of the teaching materials are that they engage children in working like scientists, encourage them to use reasoning skills and scientific thinking, maximise group discussion, and generate their own questions and ideas. By making observations and creating experiments or models, pupils derived a deeper understanding of plants and were able to explain their ideas and make more effective arguments when presenting their work.
The Plant Scientists Investigate websitew1 is divided into four topics: conservation, art, food, and experiments about plant growth. Ready-to-use teaching materials on these topics have been designed to overcome gaps in knowledge of teachers surveyed at the outset of the project. Each activity can be taught independently or in combination, and the content is easily adapted to a wide range of ages. All materials can be downloaded from the website.
Carbon dioxide in exhaled air
Children should already know that the air they exhale contains less oxygen than fresh air does. With this experiment, they can test if there is more carbon dioxide in exhaled air than inhaled air using a colour-change indicator.
To understand that the air people exhale contains more carbon dioxide (and less oxygen) than the air they inhale.
1 h 20 min
Materials per group
- 2 glass containers
- 2 straws
- 1 bike pump
- Tube with dissolved potash lye (10% KOH)
- Tube with colour indicator (phenolphthalein solution)
- Photocopies of Activity Sheets 1 and 2w2
- Film on the Plant Scientists Investigate websitew3 (optional)
- Precise working with a pipette and chemicals
- Exhaled air
- Carbon dioxide
- Inhaled air
Divide the children into groups and distribute Activity Sheet 1w2. To review the composition of air, children should colour in the different components of fresh air on the activity sheet (see teachers’ notes). Exhaled air is missing 5% of the oxygen that makes up inhaled air. Ask children to consider what may replace this missing oxygen. Ask them to consider how they could test their ideas. Scientists can use highly specialised machines in a laboratory to test, but we can still investigate air using basic equipment.
- Tell the children that the next experiment can test whether there is more carbon dioxide in exhaled air. A colour-change indicator will show if the carbon dioxide concentration in the liquid is increasing.
- Distribute the necessary materials (except for the chemicals and air pumps).
- If this is the first time that children have used a pipette, show them how to use it properly by practising pipetting water and releasing it drop by drop.
- Go through appropriate health and safety measures with the children. As they will be working with chemicals, it is very important for them to work carefully and precisely. If there is some liquid left in the pipette, it should be dripped back into the small jar (tubes). Only then should the tubes with chemicals be distributed.
- Ask the children to follow the instructions on the activity sheet on how to use the colour-change indicator.
- Before carrying out the experiment, the children should discuss what they want to find out, i.e. to investigate if the carbon dioxide content of exhaled air is different from fresh air. The pink solution (phenolphthalein) changes colour when it comes into contact with carbon dioxide.
- The children should carry out the first part of the experiment. Discuss what happened and why it happened.
- Ask the children to think about how to get fresh air into the second jar. Let them work in pairs to come up with ideas and then come together as a class to decide what to do. Distribute Activity Sheet 2w2 and the air pumps. The children should pump fresh air into the second jar. Note: the colour is not going to change (or should change only slightly).
- Discuss with the children what the experiment is designed to find out. It can show that there is more carbon dioxide in exhaled air than in fresh air.
- Complete the drawing with the fresh air.
- Ask the children to summarise two things which they discovered during the experiment.
A film demonstrating how to run this activity is available on the Plantscafe website in the media galleryw3.
Fresh air consists of 78% nitrogen, 21% oxygen and 1% of other gases (including carbon dioxide and others). Oxygen is necessary for every burning process, whether burning a candle or burning food at a cellular level.
Health and Safety
Because 10% KOH is corrosive, it should not come into contact with skin or the eyes. Children should use gloves, or this specific part of the activity should be carried out only by the teacher. Regulations on the control of substances hazardous to health (COSHH) will apply. After the experiment, the solutions in the jars can be disposed of down the drain.
For preparation and experiment methodology, see Activity Sheets 1 and 2w2.
KOH produces a slightly alkaline solution, which is coloured pink by an indicator. Exhaled carbon dioxide produces carbonic acid in the water, so the alkaline solution turns acidic (changing the pH value). The pink solution becomes colourless when exhaled air is added to the solution.
My own oxygen consumption
This activity will demonstrate to children how much green space is needed to produce enough oxygen for one person for one day.
- To work out the relationship between our daily oxygen requirements and the quantity of plants necessary to produce this volume of oxygen.
- To understand that all green plants produce oxygen.
- To understand the importance of the rainforests and seaweed for the maintenance of the gas balance in the atmosphere.
- Carbon dioxide
Walk with the children to a lawn or other green space outdoors. Ask children if they have any idea how much oxygen we consume every day.
- Explain that studies have shown that a human needs, on average, 360 litres of oxygen per day.
- Review what children have learned so far about how plants produce oxygen (what a plant needs for photosynthesis). Emphasise that all green plants produce oxygen.
- Children should guess how large a piece of lawn needs to be to provide enough oxygen for one human to live for one day. Let the children mark out their estimated area using the string.
- Explain that an area of grass of about 3 m² provides the daily oxygen needs of one human. Each group should then mark out this area of grass to visualise the area of plants that each one of them needs to produce his or her daily intake of oxygen.
- How big must the area be so that the whole class or the whole school has enough oxygen?
- Discuss the following points:
- Humans and animals live in cities where there is little green space but they still need to breathe. How can this happen?
- What happens in winter, when many trees shed their leaves?
- How can we still breathe at night if light is needed to produce oxygen?
- The rainforests and seaweeds (algae) in the sea produce and release enough oxygen to maintain the gas balance in the atmosphere. Rainforests and seaweeds are the lungs of Earth. What would happen if the rainforests or seaweeds died because of pollution?
A new ski run?
This activity puts children in a real-life situation where plant conservation and economic development clash. In an alpine setting, children play the part of citizens in a ski resort where new plans for ski slopes threaten an area rich in biodiversity. In this role play, children will develop abilities to discuss complex problems, examine pros and cons, and make decisions – and by doing so accept that one often has to compromise.
- To resolve complex problems, and help children to accept that compromise is often necessary.
- To understand that extinction is a problem linked with human action, but that humans can also help to conserve and protect threatened species.
- Problem solving
- Communication skills
- Role play material (downloadable onlinew4)
- Character cards (downloadable onlinew4)
- Sticky labels
- Coloured pens
- Photocopy of Activity Sheet 3w5
- Paper (A2 size)
- Impact of human activity
- Land management
- Personal, social and health education
- Literacy, specialised language, slogans (genre writing)
A new ski run?
This game is a role play, based around characters in a society: the mayor, hotel managers, botanists, ski-run builder, foresters and wildlife rangers. The plot is about economic development in the countryside; building a new ski slope. The full story, character cards and instructions for running the game can be downloaded from the media gallery on the Plantscafe websitew3.
- Give each child a card that describes their role at least one day before the activity so that they can begin to empathise with the character. Consider the ability level needed for each role and assign roles accordingly.
- Each child writes their character name on a sticky label and wears it during the role play.
- They sit in a semicircle to represent a real open public meeting.
- The mayor convenes the meeting at which every role player sets out his or her case for or against the construction of a new ski slope. The mayor must guarantee order and must let all representatives speak.
- Because of the complex issues discussed, the mayor declares a citizens’ referendum in which every character has a vote.
- Before any vote is made, each group has to develop marketing or promotional materials, e.g. posters, to persuade the citizens to vote for their cause. These posters/leaflets should be distributed and the representatives should have time to read them.
- A secret ballot is taken.
- The result of the vote is read out by the mayor. In the case of a split decision, the mayor has the deciding vote.
- The outcome should be discussed by everyone.
- Children should fill in Activity Sheet 3w5 to summarise their opinions.
What do we know about climate? Investigating the effects of anthropogenic global warming
- Other Science in School articles related to climate change (mostly for secondary school) include:
- Benestad R (2007) What do we know about climate? The evidence for climate change. Science in School 7: 49-51.
- Benestad R (2008) What do we know about climate? Investigating the effects of anthropogenic global warming. Science in School 8: 48-51.
- Grigorov I (2006) Bringing global climate change to the classroom. Science in School 3: 56-59.
- Sedwick C (2008) What killed the woolly mammoth?Science in School 9: 18-21.
- Shallcross D, Harrison T (2008) Climate change modelling in the classroom. Science in School 9: 28-33.
- Shallcross D, Harrison T (2008) Practical demonstrations to augment climate change lessons. Science in School 10: 46-50.
- For a full list of Science in School articles about climate change, see:
- The lead members of the Plant Scientists Investigate project were:
- Suzanne Kapelari, Institute of Botany, University Innsbruck, Austria
- Sue Johnson, Institute of Education, London University, UK
- Costantino Bonomi, Natural History Museum Trento, Italy
- Gail Bromley, Royal Botanic Gardens Kew, London, UK
- Krassimir Kossev, University Botanic Gardens Sofia, Bulgaria