Sustainability

One of The Cross Curriculum Priorities (CCP) outlined by the Australian Curriculum, Assessment and Reporting Authority (ACARA) is sustainability.
ACARA outlines the over-all goal behind teaching sustainability -
"...to allow young people to develop an appreciation of the need for more sustainable patterns of living, and to build capacities for thinking, valuing and acting necessary to create a more sustainable future." (ACARA, 2010)
In teaching sustainability to students, ACARA hopes to promote sustainable life style choices. In the geographical context, this could mean looking at the effects of unsustainable decisions in areas such as the mining industry, whaling industry and development of coastal areas and rain forests  These are large scale themes. The topic can be more localised as well - observe the effects of storm water run-off in a local area, which then has larger effects on the environment. In this way, teachers can give a small scale decision which leads to a larger scale of consequences. This will teach the geographical concept of scale.
Sustainability can not only look at the environment, but also at a range of other areas such as its extent to resources and people. An example would be looking at Australia's immigration policy in regards to population and the resources available to an expanding population.
Sustainability can must be considered in regard to the triple base line - economically, socially and environmentally. This outlines the fact that decisions must be made according to how it will affect the three areas. A sustainable decision will not compromise any of those areas in an unbalanced way.

(Ducommun, F. 2013)

Sustainability is a subject that students can be encouraged to be passionate about by encouraging them to get involved in making their school and home more sustainable. 

References - 

Australian Government. Australian Curriculum, Assessment and Reporting Authority. (2010). The Shape of the Australian Curriculum. Retrieved from http://www.acara.edu.au/verve/_resources/Shape_of_the_Australian_Curriculum.pdf

Australian Government. Australian Curriculum, Assessment and Reorting Authority. (2011). Shape of the Australian Curriculum: Geography. Retrieved from http://chc.moodle.com.au/pluginfile.php/22728/mod_resource/content/0/Shape_of_the_Australian_Curriculum_Geography-1.pdf