My sister was born in September 2010. She’s going to be in high school this autumn and one of the first freshmen to turn 15 during the school year.
I was 15 years old when I started freshman year and 16 by the end of the year, so I graduated high school at nineteen. (College grad since age 23 last year).
I was always one of the youngest in my class. My birthday is very late in the year. I also graduated high school a year early and entered college while I was still technically 16. I got the occasional joke/comment about not being able to drink until I was a senior in college.