I'm a freshman and I've been 15 since October 9th. There are a lot of sophomores younger than me and they didn't skip a grade.

Are there other kids your age that are sophomores? Have you ever been retained in a grade?

You should be in the grade you are because you have to go from one grade to the next and learn the material in each one... so you deserve to be in a grade based on mastery of the material... not because of your age. Plus a lot matters by exactly when your birthday is in the year as to which year you started school. I for example graduated at 17 because my birthday is late in the year... and I started Kindergarten at 4 as a result. There were many people that were 18 at graduation... and a few that were older than that because they failed a grade or two and had to repeat it.

The school system I was in did not alow anyone to skip years no matter how smart they might have been.

You should be in the grade you are because you have to go from one grade to the next and learn the material in each one... so you deserve to be in a grade based on mastery of the material... not because of your age. Plus a lot matters by exactly when your birthday is in the year as to which year you started school. I for example graduated at 17 because my birthday is late in the year... and I started Kindergarten at 4 as a result. There were many people that were 18 at graduation... and a few that were older than that because they failed a grade or two and had to repeat it.
And here in California we don't allow students to enroll in Kindergarten unless they turn 5 by October 1. Next year, the cut-off date is September 1, so no Kindergarteners will be 4 at all, making students older at graduation.

And here in California we don't allow students to enroll in Kindergarten unless they turn 5 by October 1. Next year, the cut-off date is September 1, so no Kindergarteners will be 4 at all, making students older at graduation.

I forget the cutoff date when I was in school... but I think it was some time in December... my birthday is almost at the END of October. Under the current California rules I wouldn't have started when I did or graduated when I did.

There was a qualifier then if you could start at 4 or had to wait until 5 based on some developmental milestones if memory serves me right.

I was already in college for several months before I turned 18.

It does not work like that, you are in a grade due to number of years you have previously passed. Or number of credits.

So some students enrolled in school at earlier age, there is no "suppose to"

How old were you when you started kindergarten or first grade? What month is your birthday? I was born in Jan so I was older than most of the people in my grade.