This is precisely the kind of garbage that I was objecting to a couple of months ago in my column in the Guardian.
Why garbage? Because some people who draw up lists of grammatical terms say that 'my' in the phrase 'my hat' is a 'possessive pronoun' (some call it a 'possessive adjective', I don't give a damn either way). Some people also call it a 'determiner' because it 'determines' 'hat'. Some don't. I don't give a damn either way.)
Clearly, it is possible in this morass, that a 'determiner', according to some, could be a 'pronoun'.
This is clearly also not my son's fault, not his teacher's fault, not the school's fault but the fault of a useless 'naming-of-parts' test which is much more about right and wrong than helping children think about language and how we put it together, use it and understand and enjoy how it works.