Could you please check this sentence for me?

Question

I am interested in student writing exchanges but my students are in first grade.
How old are first-grade students? (This is a real question)

Answer 1

The phrasing "student writing exchanges" may or may not be understood, depending on whom you're writing to. The casual term is "pen pals" but, again, that may or may not be easily understood.

First-grade students in the US are usually 6 or 7 years old.

Answer 2

im english