Scaling is not determined by the rank of your school.
What your teacher meant was that since your school consistently produce students of high quality, she expects that your class should be able to perform well in the hsc exam, such that your hsc exam marks are hopefully substantially higher than your school marks. As a result, the board of studies will moderate your school mark in order to reflect the performance of your cohort's hsc exams.
However, your teacher may be marking harsher or setting harder assessments compared to other schools and this will allow your hsc exam marks to be substantially higher than your school marks and hence your school marks will be scaled up further.
I'm not completely sure in regards to the scaling process but the above is rougly what your teacher expects to happen.
Basically this.
Just expanding further:
Your school rank is determined by the number of band 6s/number of exams sat for each HSC year - it varies from year to year. Since your school is consistently in the 50s, it produces lots of highly competent students (and yes, a school rank of 50 is excellent seeing as there are ~600+ high schools in NSW).
As such, even though your rank 1 only got 80%, that person is expected to get a higher mark in the HSC and so is everyone else in your class. This is because (as Franman said) your teacher most probably gave a hard exam relative to other schools. Therefore, when your internal marks will be aligned against other schools they should increase.
Your teacher is wrong to say it would be scaled up, it should increase due to the
aligning process. Note that aligning is different to scaling. Aligning is done by the board of studies to compare marks of different schools/students in the SAME subject, while scaling is only done on the aligned subject marks by UAC to determine individual UAIs (to compare all subjects).
