Hi to all in 9th-grade English at Fredericksburg Academy!
One thing I can quickly say is that 'Singing My Sister Down' takes place at no particular historical time, except that it must be a time where trucks and pistols are available. It also takes place in no particular country. Although the original tarpit that inspired me was in Africa, the story's not set in Africa, and it's definitely not set in Australia.
I promise to get back to you in a little while with more detailed answers. In the meantime, feel free to ask more questions if you need to, and enjoy your short-story reading!