I am a first grader at New York Middle School.

I am a first year at New York Middle School.

I am in the first grade at New York Middle School.

I am in the first grade at New York Middle School.

I am a student in Class 1-2 at New York Middle School.

I am a student of Class 1-2 at New York Middle School.

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Are all expressions correct?
Would you let me know correct expressions?

2 answers

If it is a Middle School, does it have a lst grade?

A Middle School usually includes 6-8 or 7-9 grade levels.
First graders attend elementary schools.