Last time I was there, grade school went all the way up to the 8th grade. I'm showing my age, I guess.
And btw, I'd say that that particular habit starts with some girls around 4th grade.
I remember when Jr. High School was 7-8 and maybe 9. Then it became middle school. What's with 10 year old's wearing bras? Oh well, forget it, I have other things to care about.