the information you have provided is incorrect
Think again.
Don't just stop reading when you find the bit you like.
You need to read the whole thing.
In particular, have a read of APP 12.3.
Is the school even an APP entity?
I ask because, for example, if the school is small, and does not turn over $3 million annually,
then it may not meet the definition of an APP entity (even if it behaves as though it does).
In such cases (usually small business, which could include a private school),
the APPs generally do not apply. It would however have to be a pretty small school.
Let's assume for the sake of discussion that the school
is an APP entity.
That would then suggest that the school thinks itself exempt from the requirement
to grant access, pursuant to one of the exemptions in 12.3.
Consider, for example, 12.3(d) - that is, the exemption in relation existing or anticipated legal proceedings.
This could be, for example, something as simple as a Restraining Order against a parent getting unruly on the sidelines, or as grave as a prospective action for negligence.*
An event at either end of the legal scale could provide the basis for an APP 12.3 exemption.
And that's just one example.
So, what actual reason did they give for refusing you the "extra" material?
One other thing - you paid for the teacher's work, and skill.
You did not pay for, and do not own, the teacher's "working" notes and records.
And certainly not those of, say, a school counsellor.
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* Say, for generic example, in respect the mismanagement of a sporting injury