Going through a phase : Infrared cameras in a teaching sequence on evaporation and condensation

Phase transitions are everyday occurring phenomena, but students often find them difficult to comprehend, not least in terms of the principles of thermal physics. To be able to explain phase transitions in primary school, teachers need to understand various concepts and phenomena, such as condensation, evaporation, energy and temperature. As energy is absorbed or released during phase transitions, changes in temperature can occur. Infrared (IR) cameras can thus be utilized to visually observe and explore surface phenomena such as condensation and evaporation. In line with the resources framework, we have designed a teaching sequence which involves both everyday experiences and observations through IR cameras, and which is designed to encourage students to leverage common resources associated with evaporation and condensation. In testing our teaching sequence, we presented three thermal phenomena to a group of pre-service teacher students. Two of these phenomena, namely walking out of a shower and sitting in a sauna, were anchored in embodied experiences to hopefully activate the students’ resources and to make the students pay attention to the thermally relevant aspects. The third phenomenon was less familiar, involving the condensation of water on a piece of paper. The result shows that the students managed to carry out the sequence with the three phenomena and applied an explanatory model across all three to consistently explain evaporation. However, the lack of a more general model of chemical bonding and an overreliance on the second law of thermodynamics seem to have acted as barriers for the students’ forming of a coherent understanding of both evaporation and condensation