The dingos and the fencing. The marsupials compared to the mammals from other continents. A very good story about isolation and evolution, perhaps the best. Make models of the drifting continents. The special flora of Australia at different habitats.
Some plants can be at least as irritating as animals.
The resources, geography, demography and infrastructure of Australia. Models showing the drifting of the continents separating Australia from the other continents millions of years ago. Your county educational centre.