... but I will still get the argument from colleagues and parents that the Linux version isn't what the they and the girls are used to at home.
I know. I get it a lot too. I don't want to bore the list too much with it but the answer, which you probably already use, is that that's a good educational argument for using something a bit different at school.
The job of the school is to educate them, stretch them, show them the variety of things that are in the world, introduce them to new ideas, new concepts, different way of doing things, get them to think, to puzzle out new things, to question the status quo. Not just to train them to use what they can work out for themselves at home. Indeed, giving them practice in working things out for themselves when faced with a strange new machine is exactly what is needed in schools, unless we assume computer development has stopped and there won't be different ways of doing things in ten year's time.
On past behaviour Micosoft changes UI every 18-24 months. So even if they stayed around for the next 10 years the original argument makes no sense.
It's worth repeating that last sentence in capitals, but you can re-read it. How often in the past ten or twenty years have we had to work things out for ourselves when faced with a new machine? Do we assume that there will no longer be that need? Is this not a critical life skill now? Can those who do not have it operate a mobile phone? A ticket machine? A car
20 years ago mobile phones were as expensive (and heavy) as a block of gold. So few people would have needed to know how to operate one...
radio? Even a loo in a 747 is a bit of a challenge to those without
Assuming they managed the task of getting on the plane in the first place. Let alone the difficulty they might have when they get where they are going with working out a strange language, set of customs and currency.
the investigative and deductive skills required to operate a different sort of computer.