Economist Arnold Kling points to “education reform activist Bill Costello,” who, in a Boston Herald editorial, writes that “our annual per-pupil spending in 2006 was 41 percent higher than the [Organization for Economic Cooperation and Development’s] average of $7,283, and yet American students still placed in the bottom quarter in math and in the bottom third in science among OECD countries.

Kling compares this discrepancy in educational inputs (resources spent) and outcomes (student growth)  to “international comparisons of health care spending and health care outcomes. Yet, the conventional wisdom on education is that the problem is lack of spending, while the conventional wisdom on health care is that the problem is the inherent inefficiency of our system.”
He continues,

The common thread in the conventional wisdom is that we need more government involvement. 

My own view is that these are two areas where outcomes depend largely on factors other than the services provided. Meanwhile, we have succumbed to the claims of suppliers that their services ought to be heavily subsidized. The subsidies lead to over-provision of education and health care services, well past the point where the marginal return from additional spending becomes negligible. In health care, this is known as the flat of the curve hypothesis. Perhaps the hypothesis also applies in education.