I fight an inside battle against calling my students kids sometimes. Honestly, this has little to do with their age and has a lot to do with my own inability to cope with my own advancing years.
I am successful in refusing to call or think of them as kids for two reasons.
1. I remember how much I hated it, when I was a young Soldier, when someone thought of me as a kid. Think of me as a newbie, a nug, inexperienced, even young. That was all fine. But I was not a kid. I hadn't been for years (I joined the Army at nearly 23).
2. Quite simply, they are not kids. They are 15 years my junior, but that doesn't make the kids. They are young. They are not children.