Anecdata, but this was my experience. I have a November birthday, and the school district in Massachusetts gave my parents the option of having me start a year younger than everyone or wait a year. My parents opted to send me to school a year earlier. I performed poorly, and at one point was labeled with ADHD. On the standardized tests they gave in 6th grade I scored at the 12th grade level, so I don't think my problems were cognitive as much as behavioral. Also, in high school having some peers who have been held back a grade being 15 years old while one is just turning 13 can lead to some rather unpleasant physical bullying. I often wonder how those early experiences may have limited my life.
I was so tempted to send that article to my mom, but I didn't know how she would take it.
I was so tempted to send that article to my mom, but I didn't know how she would take it.