Obviously, the intrinsic rewards of learning aren't working in New York's schools, at least not for a lot of children. It may be that the current state of achievement is low enough that desperate measures are called for, and it's worth trying anything. And we don't know whether in this case, motives will complement or compete.

But it is plausible that when students get paid to go to class and show up for tests, they will be even less interested in the work than they would be if no incentives were present. If that happens, the incentive system will make the learning problem worse in the long run, even if it improves achievement in the short run -- unless we're prepared to follow these children through life, giving them a pat on the head, or an M&M or a check every time they learn something new.

"Single-gender, public academies need to guard against becoming a new form of tracking or resegregation," a 2001 California study said. "Segregation might lead to a safe or comfortable space for some populations, but they clearly create tensions for race and gender equity."

The academic success of both girls and boys was influenced more by small classes, strong curricula, dedicated teachers and equitable teaching practices than by single-sex settings, the researchers said. This finding reinforced those of a 1998 study by the American Association of University Women that concluded that separating the sexes does not necessarily improve the quality of education for girls.