In a recent Australian article a University of New England researcher found that any advantage of holding children back from starting school was negated in English and Mathematics by the time they got to years 3 to 5. This of course may serve to answer the educational curriculum aspects of schooling but, what about emotional and physical developmental and other aspects? That is harder to establish and realistically to even research.
Malcolm Gladwell* in his book Outliers - which famously mentions that every new skill or talent requires 10,000 hours to develop makes the further argument that many sportspeople actually benefitted by starting late or at least being older in school. How?
The logic presented by Gladwell was that because children in a class are more physically developed due to their age, they tend to get the teachers attention and time when it came to sports and motor skills. This extra attention helps incrementally when taken over the 12+ year of school life to significant benefits in skill and of course recognition and confidence in terms of sporting prowess.
What are parent expectations for your schools today? What have you experienced over your teaching career? Are younger kids in your class better at academics than sports? Should you change what you do in the classroom? Does it even matter?
* As an aside, Gladwell argues that there is more to it than age - he had some compelling arguments as to why Bill Gates and Steve Jobs etc. succeeded aside from natural talent.
Hint: it was their location and access at a time computing power was limited to a small population. As teachers we know there is no such thing as level playing field but we need to keep trying.