So how about this as a hypothesis- spend the money on improving parental engagement. Weekly training events, much better planned homework (xeroxd sheets handed out is not the same as a guided syllabus for the parents to follow)
You can do a lot just by engaging those parents
But what if those parents don't want to be engaged with. A lot of children who would be "left behind" in the old school would have been from a worse social-economic background which would mean the parents just won't have time for the school events. Or they might just not care about the kids.
Have "parent trainers" for a school and i expect a massive increase in engagement - and pupil outcomes.
This of course comes at a cost.
And where parents are working 3 jobs to get buy, then yes, there is another extra cost to society - which is to ask why have we arranged society so some people are in that situation ? cf tax regieme, welfare state etc etc
I don't. For three reasons:
(1) the needed training is probably deep, not shallow, and needs years of lead time.
(2) most parents aren't sociopaths, sure, but that doesn't mean they accept an offered external authority as more knowledgeable than themselves on rearing their children, even if they actually were.
(3) #1 is only a “probably” because it's not entirely clear what the needed training is; we know parental wealth and educational attainment makes a big difference, but we don't know on a more detailed level why, and there are conflicting explanations. Having trainers may not help much of we don't know what it is that they should be training.
Say you took any poorly scored school and decided to create two schools from the student body. Same funding per child. Children whose parents come to a signup night for the new school get to go to the new school. The rest stay in the old school. The academic results from these two schools will be very different, just by this simple sorting. Money and better teachers help, but so far applying them from the outside doesn't seem to move the needle much.