As I explain in an op-ed in today's Orange County Register, that's not a theoretical question. After adjusting for inflation and enrollment growth, CA spent $27 billion more on K-12 public schooling in 2010 than it did when Jerry Brown was first elected governor back in 1974. SAT scores fell over that period (see chart below).
And if a $27 billion spending boost was associated with a decline in SAT scores, why would anyone expect Governor Brown's proposal to raise another $7 billion in education taxes to do any good?
Note that the above version of the chart includes an extra two years of (estimated) spending data from the Brown administration's current budget document, compared to the version than ran in the OCR. I'd left off those years because I didn't want to include estimates, only concrete figures, but I've already been asked about them so I include them here. The picture's the same either way.