Under the current system, the worst students cost far more to educate than the best students. Because of this you can slice the numbers to say everything from money is harmful, meaningless, or beneficial. The simple truth is in education resources matter but like all things there are significant diminishing returns after a while.
"Under the current system, the worst students cost far more to educate than the best students."
This is an excellent argument against the current system. The reason why the worst students cost more to educate using the Gary Plan is largely because of expensive pull-outs, which isn't a problem under, say, Open Systems Instruction.[1] Under the current system they actually talk about Total Adjusted Pupil Units rather than students, which shows just how pervasive the problem is.
The ROI from educating poor students is actually fairly high. The cost gap between someone at minimum wage vs. welfare vs. prison is huge. It's generally speaking much easier and more cost effective to avoid a single teen pregnancy that to fund enrichment programs.