Take picture as if you were celebrating Christmas in Australia.
Beach, sunglasses, cold drinks, BBQ
But also Christmas elements like a Santa Hat, Christmas tree, Christmas cookies etc.
And don't worry, the only one who is going to see the picture is your teacher. You do not need to do a presentation in front of the whole class.
If you don't celebrate Christmas at home, you can simply take a picture as if you were in Australia (so it's hot outside!) and leave out the Christmas elements.