The greenhouse effect: an experiment with two jars
Submitted by Camille Démo ✓, Collège Jean-Moulin, Paris · published on September 17, 2026
Understand how the greenhouse effect works through a simple experiment and interpret the measurements.
Exercise
Equipment
Two identical glass jars, two thermometers, transparent plastic film, a lamp.
Method
Place a thermometer in each jar. Seal jar A with the plastic film and leave jar B open. Light both jars with the lamp for 15 minutes, recording the temperature every 3 minutes.
Questions
Plot both temperature curves against time.
Compare how the temperature changes in the two jars.
What role does the plastic film play? What does it correspond to in the Earth's atmosphere?
Name two greenhouse gases and one human activity that releases them.
Show the answer key
The temperature in the sealed jar rises faster and higher.
The film lets light through but holds in the heat: this is the role played by greenhouse gases (CO2, CH4, water vapour).
CO2 (burning fossil fuels), CH4 (livestock farming, landfill).
Show the 3 quiz questions
Multiple-choice questions about the climate topic of this exercise. Mark the exercise as done with a class to add them to that class's quiz.
Without the natural greenhouse effect, what would the average temperature at the Earth's surface be?
- A. About −18 °C ✓
- B. About 0 °C
- C. About +15 °C
- D. About +30 °C
Which of these gases is a greenhouse gas?
- A. Nitrogen (N₂)
- B. Oxygen (O₂)
- C. Carbon dioxide (CO₂) ✓
- D. Argon (Ar)
True or false: the greenhouse effect is caused only by human activities.
- A. True
- B. False ✓
To go further
The greenhouse effect is a natural phenomenon: without it, the Earth's average temperature would be about −18 °C instead of +15 °C. Today's problem is that human activities are strengthening it.
To find out more
CO2 stays in the atmosphere for several centuries; methane (CH4) has a stronger effect but disappears within about ten years.
The IPCC reports summarise the state of knowledge every 6 to 7 years.
Possible follow-up: measure the temperature of dark ground and light ground in the sun (albedo).
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