You need to get someone who is good at writing to proofread it and clean it up. Your target audience for this piece is educated administrators, and those mistakes will stand out like dog's balls. They're friction points that should be smoothed out so that they don't distract from your message.
Re: Math/Maths, 'math' is American English, 'maths' is British English. Maybe it's bled through from American textbooks - perhaps go by whatever is on the cover of your son's textbook? Australian English can supposedly use either form, but generally it's considered to be British English, and you should stick to one or the other when you write (ie: don't mix and match).
I perhaps came across more hostile than I intended. It just struck me as notable the difference between the intent of the article and the way it was presented.
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EDIT: I've hit my comment limit, but wanted to respond to your comment with:
On the mixed audience - just remember that your primary audience is Victorian education administrators - they're the ones whose opinions you want to change. Write for your audience in the way that has least friction.
When you mix'n'match British/American English (like realise/realize), you will annoy someone in each camp. If you pick one style and stick to it, it's more coherent and the message content flows more easily. It doesn't make what you say more convincing, but it does reduce potential sticking points that might distract a reader's attention.
Good luck with your efforts. :)