It all depends on what type of adolescent unit you're going to work on, is it open or closed (locked or unlocked). Is it a private hospital or a city or a state unit. I was in nursing school when I started as Mental health tech in a privately run psychiatric hospital, the only real psychiatric experience I had was what I had seen on TV, which was really zero. In the interview, just let them know that the experience is new for you, I was hired because I was a male, and males are always needed especially with adolescents. Remember take your time and try to absorb what's being taught, it could come in handy later.