The criteria in the assessment handbook is out of twenty, but the exam score is out of 40 for each essay (I think because they are marked twice by different assessors). Percentage wise 1 exam essay is the equivalent to one semester of SACs.
I got a 35 for Literature last year, I got A's for my semester 1 and 2 SAC's (according to VCAA), the marks given to me by my teacher worked out to be in the mid/high 90's (/100) for each semester, but they were moderated down to about mid 80's due to my cohort, and then my exam score was 60/80 (30/40 for each essay) which was a B+, but the cut off for an A was 61+ (

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It's all pretty subjective; the marks your teachers give you and the marks you get at the end of the year from VCAA can be wildly different. Rather than focusing on your study score, you should just make sure that you walk out of each of your SAC's feeling content that you tried your hardest. When it comes to the exam, it doesn't matter if what you write in the exam is a work of literary genius, ultimately only two random assessors will read your paper, to whom you are an anonymous number. Studying literature is a pleasure, just make sure that you enjoy it!
Also, it would be very good to spend some time on the internet just searching for and reading reviews of the books you're doing
This is excellent advice, however, some of the texts on the lit textlist are pretty obsecure and have few online resources. So try books too! If you are a member of your local libary (you should be, doing lit and all) you can use this:
www.llv.net.au/ which lets you search pretty much every libary book in Victoria.
Demongleekgazza - I would reccomend
Dario Fo: stage, text, and tradition, if you haven't already got it, for Accidental Death.