The move to clarify, unify and quantify what is taught in public schools has invaded early childhood education. Forty states have adopted standards for preschool education, goals that are intended to shape, and likely standardize, what is taught within the classroom. Another 40 fund some public preschool programs, with Georgia and Oklahoma providing free preschool to all 4-year-olds. And with money comes accountability.

Legislators like things that can be measured in hard, cold and preferably simple numbers, but many early childhood experts don't cotton at all to the notion of summing up young, wildly diverse children in any sort of score. They're especially uneasy over a massive program to test nearly a half-million preschoolers in Head Start by 2006.

It makes sense to define what a quality preschool program is, to arrive at some agreement on what kids need in preschool and to make sure that they're getting it. But the notion of making preschool more "school" and less "pre" - of funneling young children into the world of results-driven learning - should send a chill through us all.

Deborah Leong, a research fellow with the National Institute for Early Childhood Research, says one of the greatest threats is that the preschool curriculum will be built around what is easily tested - knowing letters, for example, or identifying colors or shapes - instead of more important underlying skills. "It's the skills that really make the learning effective - the ability to focus their attention, to be able to remember things on purpose, to control their emotions, to think ahead to consequences," Leong says. "We can end up producing children who can only learn by memorizing things, not by thinking abstractly and developing the skills to be a good learner later."

Both NIECR and the National Association of the Education of Young Children urge great caution in testing preschool children and making preschool experiences too rigid or uniform. We hope legislators and educators will take note. Like that fleeting thing called childhood, preschool should be a place where being a happy, healthy, curious kid is enough to master.