When I was...??

Many many Japanese people say:

When I was a high school student...
When I was a junior high school student...
etc.

This is perfectly correct English...however, this is better and simpler:

When I was in high school...
When I was in junior high school...
etc.

Native English speakers don't really say "When I was a high school student..." So it sounds a little awkward.

examples: When I was in college, I played volleyball.
              When I was in elementary school, I met my best friend.