Sustainability (as a context for teaching aspects of heat transfer and energy)
There are three activity ideas here.
Solar funnel cookers can be used in a unit on conduction, convection and radiation.
Zeer Pots work by evaporation.
Hand generators demonstrate energy transfer and can link with wind-up radios.
See also here.
The activities can form a suite of lessons on the theme of sustainability or can be used individually at appropriate points in a course.