Hell I'm already in high school, so I guess I'll try to explain from a middle schooler point of view.
Answer (Copy this):
My feelings about going into high school is a little scared and nervous because what if high school is completely different from middle school? What if there's gonna be seniors and unfriendly upperclassmen that could pick on me for being a freshman? What I'm looking forward to in high school is getting new friends and possibly going to prom when I get older. Also it'll be fun to try out all the new fun activities in high school that middle school probably didn't have. What I'm scared about high school is what if the inside of the school is so confusing to the point I can't get to all my classes? And what if I can't get to all my classes on time and I get lunch detention or even normal detention? Even though high school sounds big and scary, I think I'm going to enjoy it after all.