Many parents and educators swear by the practice of "academic redshirting" -- waiting an extra year before enrolling a child in kindergarten in hopes of giving the kid more confidence, greater size or perhaps an academic edge.
But does it really work?
New research -- including a federal study of 21,000 youngsters released in May -- suggests that the benefits are a mixed bag, both academically and socially. As often happens with education techniques, redshirting appears to help some, harm others or have no effect at all.
For Suzanne Weerts of Burbank, the value was clear enough. As her son Jack neared his fifth birthday last September, his parents sought out teachers and other parents to help them decide whether their boy was ready for kindergarten.
Eligibility wasn't an issue: The Burbank Unified School District's cutoff birth date is Dec. 2 and Jack was born on Sept. 15. But Weerts worried that her shy son would be intimidated by children who had turned 5 months earlier and would have a tough time keeping up academically.
This September, Jack will start kindergarten at William McKinley Elementary School and is likely to be one of the older kids in his class.
"In preschool he was a follower," said Weerts. "This year he was a leader in the classroom. He's more confident. You can't go wrong with the extra year."
Weerts said that, among her friends, about half opted to give their children an extra year. It's a decision lots of parents have to make as fall approaches. And a lot are deciding to redshirt, a term borrowed from sports lingo, where freshmen athletes are held back a year to give them more time to build strength.
The concept isn't new, but it's impossible to say how common it was, say, a generation ago. Recent national studies estimate that 6% to 9% of children eligible for kindergarten are redshirted each year. Research and anecdotal reports have found that, in some school districts, as many as 50% of kids are held back an extra year before starting kindergarten.
Some kids benefit, but others don't.
That was the conclusion of the report on 21,000 children released in May by the U.S. Department of Education. The study of boys and girls entering kindergarten in 1998 looked at their abilities when they were in first grade. It found that the children who had been redshirted had lower math knowledge and skills than first-graders who started kindergarten on time.
"It's always done with huge amounts of love and passion," said Elizabeth Graue, professor of curriculum and instruction at the University of Wisconsin at Madison, of the practice.
"The problem is that it doesn't always necessarily pay off the way you think it's going to," said Graue, who has done extensive research on redshirting.
Repeating kindergarten, the federal study also found, was an even more harmful practice.
By the time they reached first grade, kids who had repeated kindergarten appeared less likely to possess specific math skills than the typical first-grader. In addition, they were less likely to have developed reading skills, such as understanding words in context.
One possible explanation: If a child had trouble mastering a subject the first time around, teaching the child with the same technique won't help much a year later.
"Typically, just repeating the same treatment doesn't work," Graue said.
Other studies have looked at the possible long-term influence of redshirting.
In 2003, a literature review of studies on redshirting by Hermine H. Marshall, an emerita professor at San Francisco State University, found that, on average, the effects of delaying kindergarten dissipated later on in grade school.
Although redshirting might help -- or harm -- a child soon after kindergarten, things start to even out by about third grade.
So, according to some research, redshirting isn't necessary because younger kids can benefit from being around older ones. Children learn from one another, and the stimulating environment of school sometimes helps younger kids catch up with their peers.
Socially, the effects of redshirting are mixed. Some studies show that older children could feel awkward about reaching puberty before their classmates. Conversely, other studies say that being older could raise a child's confidence and popularity.
For some parents, the social pressures of middle school and even college were on their minds when they redshirted their kids before kindergarten.
"Just think if you want your child to be the youngest ninth-grader, trying to keep up with the older kids and being more susceptible to peer pressure," said Calissa Ricker of Burbank, whose daughter Isabel, 8, was redshirted. "Do you want them to be the confident ninth-grader or the timid one?"
In some cases, parents may be pressured into giving their kids an extra year by teachers or school officials hoping to ensure classrooms that are easier to control.