This sub_unit analyses the transfer of thermal energy due to a bulk, macroscopic movement of matter (fluids or gases) from a hot region to a cool region.

The starting point is the analysis of Activity 1_2 of sub_Unit_1 that will be supported by further observations performed in Activity 3_1 whose objective is to make evident the currents of hot fluids moving from hot to cold regions.

This activity will end by supplying an explicative model, i.e. a qualitative  mechanism of functioning explaining natural convection on the base of density differences among fluid volumes at different temperature. Such a model will be used in order to explain the “stack effect” or the “chimney effect”, where rising hot air pushes outward at the top of a building and cold air is drawn inward at the bottom.

A second activity (Activity 3_2) will analyse the effect of moving air on surface temperatures by confronting results of two experiments measuring natural cooling and forced cooling. Data can be analysed at different levels by characterising phenomena qualitatively or quantitatively in dependence of the classroom mathematical knowledge.

The following table characterises the two activities from the point of view of the required type of inquiry and considering 5E model of the Learning Cycle.

Student level: 
Lower secondary school level, students of age 11-15.
Estimated duration: 
5-6 class periods