Are you sure because I heard that class assessment marks don't count because different schools set different difficulties..?
You should have an assessment schedule with all the assessment tasks for all subjects and their weightings. These will be set by your school and internally marked.
When this process is finished - around late August, early September - your school will have a mark out of 100 for 2 unit subjects or 50 for 1 unit ones that they send into the BOS. This is the mark used to determine your moderated assessment mark. In order to ensure that the school's marks are comparable across the state these marks are moderated using the final HSC mark by giving the highest exam mark as the top moderated assessment mark and the lowest exam mark to the lowest ranked student as their moderated assessment mark. The rest of the cohort are allocated marks based on the relative gaps between them and those around them (not a direct correlation of third exam mark to third ranked student at all). This way the internal marks can be compared across the state. This also stops schools sending in exorbitant marks. Look at the following sets of marks:
School A sends in 5 students with the following 5 marks - 98, 95, 92, 89 and 85
School B sends in 5 students with the following 5 marks - 88, 85, 82, 79 and 75
It would appear that School A's students are better than School B's but what is School A sets easier tasks - the BOS needed to find a way to be fair so they moderate them.
Now what if the students at both schools ended up with the following set of marks:
96, 95, 93, 92 and 89
Final result would be the same for both schools as it seems that School B's set harder tasks - the total marks, average, range and median for both schools in the HSC was the same and so were the range and relative gaps so in both schools the top ranked student would have a moderated mark of 96 and the bottom would end up with an moderated mark of 89 with the gaps in between also staying the same between the schools.
Class tests that aren't mentioned in the assessment schedule don't count however.
This internal moderated mark contributes 50% to the final mark and the other 50% comes directly from the HSC exam itself.