http://www.nytimes.com/2011/09/25/opinion/sunday/dont-delay-your-kindergartners-start.html
Delay Kindergarten at Your Child�s Peril
By SAM WANG and SANDRA AAMODT
New York Times
September 24, 2011

THIS fall, one in 11 kindergarten-age children in the United States will not be going to class. Parents of these children often delay school entry in an attempt to give them a leg up on peers, but this strategy is likely to be counterproductive.

...

Teachers may encourage redshirting because more mature children are easier to handle in the classroom and initially produce better test scores than their younger classmates. In a class of 25, the average difference is equivalent to going from 13th place to 11th. This advantage fades by the end of elementary school, though, and disadvantages start to accumulate. In high school, redshirted children are less motivated and perform less well. By adulthood, they are no better off in wages or educational attainment � in fact, their lifetime earnings are reduced by one year.

...

Parents who want to give their young children an academic advantage have a powerful tool: school itself. In a large-scale study at 26 Canadian elementary schools, first graders who were young for their year made considerably more progress in reading and math than kindergartners who were old for their year (but just two months younger). In another large study, the youngest fifth-graders scored a little lower than their classmates, but five points higher in verbal I.Q., on average, than fourth-graders of the same age. In other words, school makes children smarter.

The benefits of being younger are even greater for those who skip a grade, an option available to many high-achieving children. Compared with nonskippers of similar talent and motivation, these youngsters pursue advanced degrees and enter professional school more often. Acceleration is a powerful intervention, with effects on achievement that are twice as large as programs for the gifted. Grade-skippers even report more positive social and emotional feelings.

These differences may come from the increased challenges of a demanding environment. Learning is maximized not by getting all the answers right, but by making errors and correcting them quickly. In this respect, children benefit from being close to the limits of their ability. Too low an error rate becomes boring, while too high an error rate is unrewarding. A delay in school entry may therefore still be justified if children are very far behind their peers, leaving a gap too broad for school to allow effective learning.

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The same authors recently wrote the book "Welcome to Your Child's Brain: How the Mind Grows from Conception to College", which may cite research supporting the above claims.

I loved that article until I got to the part about school making (younger) children smarter. Talk about correlation without causation! That assertion is grade-AA bogosity. There was no mention of the possibility that redshirted kids get that way because mom and dad see (quite rightly in many cases) that their child isn't ready for kindergarten yet. What bothered me this article is that this particular reason for redshirting comes up all the time. It goes something this: Kindergarten, with its new emphasis on academics, is not the "children's garden" it was a generation ago. It's becoming the new first grade, and many parents opt to hold their kids out for another year so that they can be ready for the demands of the new kindergarten.

Here's an example.

Here's another one.

And the implication that the grade skip is responsible for pursuing advanced degrees is equally silly. The authors don't seem to see the connection between skipping because you're very smart and getting a PhD because you're very smart.

"The benefits of being younger are even greater for those who skip a grade, an option available to many high-achieving children. Compared with nonskippers of similar talent and motivation, these youngsters pursue advanced degrees and enter professional school more often."

Well, technically they are saying that they compared the skippers to similar non-skippers so the effect should be from the skipping itself.

HOWEVER, I question their ability to really do this in the study. How did they measure the similarity in talent? If they just took the top 3-5% of a grade level achievement test score, for example, we have no way of knowing if the two groups are "similarly talented" because any variation between very bright, gifted, HG, PG, etc. is hidden.

I do appreciate the argument about how important it is to teach kids at a challenging level, however.

Also, they don't address the issue of preschool in the article. While the kindergarten age has gone up, kids are much more likely to attend preschool than they were a few decades ago. So kids are not necessarily getting less schooling. Also, kinder is much more likely to be full day now. So, you could argue that preschool is replacing the old half day kinder and kinder is being added as a new "grade". So in fact, kids are getting MORE schooling than in previous years. That said, I would think that NOT going to preschool would be a disadvantage today possibly.