I haven't been marking them as such, just looking at questions i struggled with and learning where i went wrong. I don't believe trial or past exam results are anything to go by at all. I'm just making sure I can do all of the kinds of questions that are likely to be on the exam.
The thing is...there's more to acing the exams than just being able to do all the questions. Being able to do all the questions is no where near enough for a 50, since VCAA exams aren't going to be so hard as to contain questions that will stump 99.5% of students. Acing the real exams is actually about avoiding losing marks to little stupid things like states, significant figures, wrong stoichemetric ratios, H2O as a product for esterification/condensation reactions, etc. And to do that you need actual practice under simulated exam conditions. Also consider that some of these trial exams and VCAA 2009 are challenging to finish within the 90 minute time-limit.
And lol I would say that trial/past exam results are a fairly accurate indicator. Most likely your real result will be equal or a little bit less than your best trial exam performance.
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After doing each exam I go into really indepth analysis of the mistakes I made and record my marks and time I took. During analysis I figure out how to ensure I don't make the same mistakes in the future, so that if I repeated the paper I would get 100%. As well I list unfamiliar bits of theory that I have encountered in the exam, and figure out how to improve the explanations I made for any explanation questions in the paper.
It works la. I went from losing 13 marks on my first chem trial, to about 3 in the last few.