At or near the start of every school year, I get calls and notes for parents demanding a waiver in order to get their children into kindergarten early, even though the children are too young to meet the age cut off. Grandparents often add their weight to the parents' request to ignore statutory and policy limits on students' age of admission to school. They often circumvent school officials and appeal to board members, or migrate to charter of nonpublic schools to get what they want.
Regardless of my remonstrations and solid research to the contrary, families usually remain adamant about their decision to take an action that usually carries less than positive lifelong consequences for most children. Logic seldom applies or prevails.
The simple truth is that students who are in the upper two quartiles of their kindergarten class age range do better at nearly everything than those in the bottom two quartiles for the rest of their lives. The developmental range at kindergarten age is large, given a normal population. Extreme outliers notwithstanding, by definition, half of the youngsters will function below average and grade level and half will be above. This applies interactively to all aspects of the school curriculum: intellectual, social, emotional, motor and others.
What is in the best interest of students and what should parents do?
I usually recommend that students remain in preschool until they are at least in the upper half of their kindergarten class age range. The upper quartile is even better. At this age, even a few months can mean a big difference in performance. It is always better to show up prepared.
Students who are the youngest often end up struggling to compete with their older class peers and almost never catch up as they move through school, grade by grade. Both groups continue to learn, but the oldest students in the group perform on a steeper and increasingly divergent trajectory compared to the youngest and this continues all the way through school. This is one of the primary reasons that more than 35% of our high school graduates are functionally illiterate. There are exceptions, but not many.
Parents of younger students should consider an additional year in preschool in order to join the next year's cohort with another year of maturation in place. Absent an available preschool program, a year of home schooling would be preferable, if for no other reason than the additional perceptual-motor development that comes with the ticking clock of the aging process.
All children develop in a cephalocaudal and proximodistal manner, ie., from the head down and spinal midline out, but not at the same rate. Not all children walk at the same age, have the physiological development to potty train at the same age or begin using verbal language at the same time. Many of the youngest may be unable to compete with others in their class curriculum, regardless of how hard they try. The physiology simply may not be present for them until later. In the early years, even a few months can make a big difference.
The age-related differential in student performance is cumulative and becomes virtually insurmountable over the course of a school career. Our highest performing high school students are nearly always the oldest within their classes. This applies to performing and fine arts; social skills; advanced verbal and computational skills as measured on ACT and SAT, as well as tests of academic achievement; and motor skills, including most athletic endeavors. (Most of our highest performing college and professional athletes are those who went through school and the athletics system in the upper quartile of their cohort age group).
Rather than rush students into a developmentally unfair and less-than-level playing field, we should more carefully apply what we know about developmental differences and take advantage of differential starting times. If there is a time to look at moving faster, it is at the upper end of the school experience where high performing students should be increasingly taking advantage of moving through the P-16 system in step with their own demonstrated readiness and rate to begin two-year and/or four-year college during what are now the high school years. About a third or so of our high school students are intellectually ready to begin college courses by age 15 or 16, another third are probably matched to the traditional timeline for post secondary experiences and another third or so should stay in the academic oven for another year or more until they are baked all the way through.