Hey!
Last year for the prac piece we had to write a discussion on the topic of "what material is the best insulator." On the information sheet there was a method, diagram of the setup, and results. There were guiding questions however you were expected to write a paragraph and address those questions in that paragraph. It wasn't really an 'essay.' I can't really find the exact prac on google but the basic idea was there was 3 styrofoam cups with water and a thermometer. The top of the cups were covered in cling wrap and each cup was covered in a different material such as foil etc. At certain time intervals, the temperature of the water was recorded.
For the second essay we got information on fish deaths in the Murray Darling Basin, and had to write an essay on that.
Prac report preparation: Take a look at the pracs in your science textbook. You should also write prac reports on all the pracs that you do at school. We used the Pearson Science book at school and most (if not all) of the pracs had discussion questions.
Essay preparation: Writing task 1 in the GAT is a good idea. Last year, the topic was about mars so try that one out. However unlike the GAT, you need to use BOTH the information given AND your own knowledge.
https://www.vcaa.vic.edu.au/Documents/exams/GAT/2019/2019gat-cpr-w.pdf