I receive more calls from reporters, parents, school board members and state officials about kindergarten entry than any other topic. Entry-age debates generate angst and opinions and too-often are not grounded in facts.

Here’s the rub: children really differ from one another in skills and interests as they start school. They differ at 6 or at 4, or anywhere in between. A cohort reflects at least a whole year of developmental difference no matter the cutoff. States that start later have similar problems as states that start earlier. Variation is the reality of human development.

It would be nice if a test could say “this child is ready for kindergarten” or our kindergartens accommodated every nuance, facet and extent of difference among children. We don’t have either. And if we did, what other debates emerge? Imagine the perfect test preventing access for kids whose skills didn’t meet the bar. And would we open up perfectly individualized kindergartens for wunderkind 3-year-olds?

The challenge of the situation is largely about equity: the possible boost for disadvantaged 4-year-olds by extra months in kindergarten. But why are these kids not enrolled in a potentially more educationally appropriate pre-kindergarten program that should actually boost readiness skills and close gaps at the start of school? To me, the most important questions are about whether we have good and effective early education programs that enroll all eligible children and bridge early childhood programs, like Head Start, with kindergarten through second grade.

Arguing about shifting entry dates might reduce a little of the variation among children in a classroom, but no entry date solves the real problems of ensuring an effective early education experience for all kids, particularly those most vulnerable, whose chances have been disadvantaged from the start.