The greenhouse effect is often associated by students to concepts like the ozone hole or UV rays and also perceived strongly negative for the Earth. Many students do not know that if Earth’s atmosphere did not have greenhouse gases, the temperatures would be so extreme that would not allow life on the planet, and if the greenhouse gases were too much, it could lead overheating. To better understand the role of greenhouse gases, the Institute of Biometeorology of the National Research Council developed a didactic module to clarify the properties of greenhouse gases and non-greenhouse gases under a radiation surce.
The activity is appropriate for students from 1st to 3rd year of all kinds secondary school and suits with science curriculum. Students, divided into groups, compare 5 different conditions in which variables (if any) change one at a time. For example, using the same kind of materials (bottles, light sources, thermometers), they compare the temperature change of different gas mixtures injected into bottles and heated by a glowing lamp. Helium, vacuum, ambient air and air with added water vapor and carbon dioxide are compared. The experiments demonstrates how the greenhouse gases, when put under a radiation source, lead to prolonged heating, especially compared to helium and vacuum.
The results obtained by the different groups are elaborated and compared in a plenary discussion where the professor acts as moderator. Vacuum and helium experiments aim to make students understand that the Earth, without greenhouse gases in the atmosphere, would lose heat quickly, while in the contrary, with a higher amount of greenhouse gases, like water vapor and especially carbon dioxide, it would take more time to cool down.
The activity can also be used to explain the evolution of the Earth’s planet, strictly connected to the evolution of its atmosphere.
The activity was tested with approximately 120 students in Italy and in Spain. In general, students learned how to carry out a science experiment and those who freely set up the experiments by their own, identified the environmental and technical variables affecting the comparison of the results of different groups. Therefore, they understood the importance to use the same setting. However students enjoyed setting up the experiment, while the biggest difficulties were encountered by those who did data processing with spreadsheets. Interviews and in classroom observation, showed how students enjoyed investigation and interest in the topic.
How to use the activity
The activity can be found on the MisstoHit website translated into 5 languages (Italian, Spanish, Basque, Catalan and Dutch).