were i live you would be either a freshman(9th grade) or sophomore(10th grade).
So i will explain what schooling is like were i live(it differs per state and area). In my school elementary school is k-5th(some places its k-6 or k-8).
Elementary school:
Kindegarten(K)- 5-6
1st grade- 6-7
2nd grade- 7-8
3rd grade- 8-9
4th grade- 9-10
5th grade- 10-11
Middle school is usually 6-8grade (some places are 7-8(usually called junior high), or no middle school/junior high at all)
Middle school:
6th grade- 11-12
7th grade- 12-13
8th grade- 13-14
High school are your last 4 years of schooling before you can either go on to college for a specialized area of the career you want, or you can just get a job) In high school you have to complete so many credits to graduate(usually 1 credit per term. There are 4 terms in a year) at my school you need 60 credits total(4 history credits, 4 science credits, 4 math credits, 4 communications(sometimes called language arts or english its basically a grammar type class) and then you need so many credits in electives(extra classes like gym, or tv production ect) unlike many countries there are no final examinations though if you want to go on to college you need to take the SAT or ACT which tests you on enlish, science, math and maybe history? i cant remember :p
high school:
9th grade(freshman)- 14-15
10th grade(sophomore)- 15-16
11th grade(junior)- 16-17
12th grade(senior)- 17-18
Some of this info is diff. depending on were you live in the USA or how old you were when you went to kindergarten or if you failed a class, were held back or skipped ahead a grade.