Subject Selection, Scaling, and Rankings: What Every Parent Needs to Know
Here's two things almost every family seems to think when their child is heading into the HSC years:
The way to a good ATAR is to pick high-scaling subjects.
Marks on exams are a good indication of what a student’s ATAR will be.
Both are misleading.
Here's the truth, and what you should know as a parent.
What the ATAR actually is
The ATAR is a ranking, not a mark. An ATAR of 90 means a student is ranked in the top 10% of NSW. An ATAR of 99.95 is the highest possible.
How the ATAR is built: the 10 units
Most HSC subjects are worth 2 units. Extension subjects (like Maths Extension 1, English Extension 1) are worth 1 unit each. Most students study somewhere between 10 and 12 units total in Year 12.
UAC takes a student's best 10 units to calculate the ATAR.
The rules:
2 units of English are compulsory. They must be included even if English is that student's worst subject.
The next 8 units are taken from the student's remaining best subjects.
This is why students often take more than 10 units in Year 12. It gives them a buffer. If one subject goes badly, it can be dropped without affecting the ATAR.
Subject choice: play to strengths, not scaling
The most common piece of bad advice I hear all the time: "Pick high-scaling subjects to boost your ATAR."
It is partly true that some subjects moderate up and some down.
‘Harder’ subjects like Math Extension, Chemistry, Physics tend to scale up. Subjects like Visual Arts, Standard Maths, and Standard English tend to scale down.
So in theory, picking hard subjects should mean good scaling and a good ATAR, right?
In reality, this is a trap.
Failing in a difficult subject, no matter how good the scaling is will not mean a good ATAR.
I can tell you this from personal experience.
I did no extension subjects, no Chemistry, no Physics - none of that.
In fact, one of my subjects was Visual Arts, commonly thought to have "bad scaling."
And yet, I graduated with a 99.55 ATAR.
The reason: I was at the top of Visual Arts. I was good at it, I enjoyed it, and so I performed well.
When picking subjects, students should play to their strengths.
Marks vs rankings
When school reports come home, we tend to look at the number. 78 in English. 82 in Maths. 71 in Economics. These numbers actually tell you very little - and can be misleading.
School assessment marks get moderated before they're used in the ATAR. NESA looks at how a school cohort performs in the HSC exam, then adjusts the school's internal marks to match. If the school does well in the exam, the marks get adjusted up. If the school does poorly, the marks get adjusted down.
What this means: a student’s ranking matters far more than their marks.
So when your child comes home with a 78 in English, the right question isn't "is 78 a good mark?" It's "is that a good ranking?"
What to focus on as a parent, and when
In Year 10 and 11 (subject choice): Ignore the fear-mongering you see online and people who claim that taking subjects with "good scaling" will guarantee a good ATAR. Your child should pick what they are naturally good at and enjoy enough to study for two years. The strongest ATARs come from students who picked well, not students who picked "tactically" and tried to beat the system.
Throughout Year 12 (school assessments): Ask about rankings, not marks. The mark alone doesn't tell you much. Their ranking within the cohort tells you the truth about how your child is performing in each subject.
Written by Jessica Crawley — 99.55 ATAR, College Dux, State Ranker, and founder of DesignTo99. I coach NSW Year 10–12 students to build study systems that work.