Throwing money will not solve this. As it stands now, you could redesign the way schools work and wind up spending less.
For example: Rather than cram everything on a kids plate in one school year and ignore teachers and students telling you they have no time to help those who fall back, why not structure school so kids don't waste time doing subjects they excel at?
If your child is in 5'th grade but reads at a college level, what good is reading some Goosebumps book gonna do for them? That portion of study should be shortened, and more time should be put on the math.
You don't even need to perfectly tune it to all students. Just have three tracks.
Skilled readers and writers.
Skilled mathematicians and sciences.
??? Make up another track.
Skilled readers will spend more time on their weaker subjects.
Skilled Mathematicians the same. They will spend more time writing and reading and communicating.
That is just a spitball idea off the top of my head with absolutely no research at all, but I am sure that it beats the current system we have. And that is sad.