Teaching overview

Learning points

  • Cattle and other farm animals release more greenhouse gases than every car, train and plane put together.
  • When greenhouse gases build up in the atmosphere, they trap more and more heat and add to the problem of global warming.
  • Reducing meat consumption and improving farming methods are two ways that we can limit the environmental impact of cattle farming.

Curriculum keywords

  • Greenhouse gases
  • Global warming
  • Farming food
  • Digestive system
  • STEM

Multimedia toolbox

Cows visual

Show the visual before the film to spark a discussion about why we farm animals, and the impact farming can have on the environment.

Farting audio loop

Play the audio loop before the film and ask the class to discuss why animals expel gas.

Greenhouse effect visual

Show the visual after the film to summarise how greenhouse gases in Earth’s atmosphere trap the Sun’s heat.

Global warming
An overall rise in the Earth’s average temperature over a long period of time.
An overall rise in the Earth’s average temperature over a long period of time.

Global warming

Show the visual after the film to reinforce scientific terminology.

Spark a discussion

  • What impact does farming have on the environment?
  • Where did the food you ate for breakfast/lunch today come from?
  • What is the problem with cow farts?
  • Why do you think cattle and other animals (including humans!) burp and fart?
  • What are greenhouse gases? Why do you think they are called greenhouse gases?
  • How do greenhouse gases damage the environment?
  • What is global warming? Why is it a problem?
  • In what sorts of ways do humans add to the problem of global warming?
  • How else might food production have an impact on the environment?
  • Do you eat meat? Why/why not?
  • Do you think people should reduce the amount of meat they eat?
  • Would you want to eat a burger made from meat that was grown in a lab? Why/why not?

Activities

The greenhouse effect

INVESTIGATE and model the greenhouse effect using a transparent plastic bag and two beakers of ice water.

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Other activity ideas

  • RESEARCH and compare human and cow digestive systems, and then create labelled/annotated diagrams for each.
  • RECORD the different lunch options on the school cafeteria menu every day for one week, identifying where the different ingredients come from. You could also work out how much food is needed to feed the whole school each day, each week, and each year.
  • CREATE an advert convincing people to buy and eat lab-grown burgers, or convincing people to eat less meat. This could be a drawn poster, a sung radio jingle, or an acted-out television advert.
  • OBSERVE how some chemical reactions produce gas, by mixing 2 tablespoons of bicarbonate of soda and 100 ml of vinegar in a bottle, then placing a balloon over the neck of the bottle and observing what happens. Similar chemical reactions occur during digestion, producing gas that must be expelled from the body.
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The greenhouse effect

Duration: 90 minutes

Resources:

  • per group
  • 2 beakers
  • 2 thermometers
  • A transparent plastic bag
  • An elastic band
  • Iced water

Key Learning:

This investigation helps the students to understand that greenhouse gases in the atmosphere trap heat.

Activity instructions:

  1. Organise the students into groups. Give each group 2 beakers, 2 thermometers, a transparent plastic bag and an elastic band.
  2. Explain to the class that they are going to explore how the greenhouse effect works. They will use a transparent plastic bag to represent Earth’s atmosphere, and observe how this affects the temperature of a beaker of iced water.
  3. Partly fill the groups’ beakers with equal amounts of iced water. Ask the groups to place a thermometer in each beaker and record the starting temperatures.
  4. Ask the groups to carefully wrap one of their beakers in the transparent plastic bag and secure with the elastic band.
  5. Tell the groups to place their beakers side by side in a sunny location such as a windowsill, making sure that they both receive the same amount of sunlight.
  6. Ask the groups to predict which beaker will warm up quicker.
  7. Ask the groups to record the temperature of each beaker every 10 minutes for around 1 hour. Note: If time or resources are limited, simply record the temperatures at the start and end of the hour.
  8. Discuss the results as a class. You can use the following prompt questions:
    • Were your predictions correct?
    • Why do you think the beaker in the plastic bag warmed up quicker?
    • How does this relate to greenhouse gases in the atmosphere?
    • How would you improve this investigation if you were to do it again?
  9. Explain to the students that both beakers received the same amount of heat from the Sun, and this heat caused the temperature of the iced water to rise. The plastic bag trapped some of the heat, causing that beaker to warm up quicker. This is similar to the way that the glass walls of a greenhouse allow sunlight to pass through, then trap some of the heat inside. Greenhouses gases in the atmosphere act the same way: they trap sunlight close to the Earth, making it warmer.
  10. Ask the students to create a graph of their results, and then write a short description of their observations and how this relates to greenhouse gases.

Background information

  • Greenhouse gases are gases in the atmosphere that trap heat close to the Earth’s surface. The main greenhouse gases are carbon dioxide, methane, nitrous oxide, ozone and water vapour. These gases act like a blanket around the Earth, keeping it warm. Without greenhouse gases, Earth would be too cold for humans to survive.
  • When greenhouse gases build up in the atmosphere, more heat is trapped and temperatures start to rise. This is known as global warming. Throughout history, the planet has experienced periods of natural warming and cooling. However, temperatures are now rising at a much faster rate than ever before, and most scientists agree that this is due to human activities. For example, burning fuels like coal, oil and natural gas releases large amounts of carbon dioxide. The meat and dairy industries produces more greenhouse gas emissions than all forms of global transport combined.
  • Cattle and other livestock release large amounts of methane in the form of burps and farts. The methane is produced during the digestive process, as microbes in the animal’s gut break down food. Cows, goats and sheep are ruminants, which means they have four stomachs to help them break down difficult-to-digest grass. The gas produced during digestion is then expelled from the body. There are around 1 billion cattle, which adds up to a considerable amount of methane.

Glossary

Greenhouse gas
One of several gases in Earth's atmosphere that trap heat close to the planet's surface.
Global warming
An overall rise in the Earth’s average temperature over a long period of time.
Atmosphere
The mixture of gases that surround a planet.

Explore our resources

Complete your lesson with teaching resources on climate change from Tigtag.

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Discover free online CPD for primary science from Reach Out CPD.

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