Those glowing statistics come from tiny studies (58 children) of places like Michigan's Perry Preschool. But those low-income, low-IQ kids got much more than preschool, including after-school tutoring, and their moms and dads got parenting classes.

Lisa Snell, education director of the Reason Foundation, says you can't expect similar results with middle- and higher income children.

In addition, lots of studies say the preschool effect fades. Head Start is revered for raising test scores, but studies show that by grades 3 or 4 those gains vanish.

"They can't tell the difference between the kids that went to Head Start and the kids who didn't," Snell says. "When they compared them to the kids that are disadvantaged that didn't go to Head Start, they can't tell from their test scores which kids had the treatment of Head Start."

There's still another flaw in the program. Some studies have found that too much school may lead to disruptive and aggressive behavior. Libby Doggett, who leads one of the biggest pre-K advocacy groups, concedes that, but claims that "high-quality" government programs benefit children. She said Oklahoma and Georgia have them already.

But those states, despite spending billions of tax dollars on preschool for the past 10 years, have not shown impressive results. Oklahoma's students lost ground to kids from other states.

Doggett replied: "We don't want to just focus on IQ scores. We want to look at how children are doing in their social and emotional, their non-cognitive development."

Please. When the huge government program fails to raise scores, the central planners promise it will help the kids socially?

Give me a break.