Extend the Story - Add a Room

Okay I'll use a knife. I have a few knifes in my room let me go get them
All right, so I have an eight inch one, and another smaller one that's six inches. My friends at school always tease me about my knifes. I have more in the attic but I use these two most often. There's this one girl in my class that is really annoying and I hater her very much. Once I threatened to kill her with one of my knifes because she was annoying me so much. She started laughing like crazy. The next day when I came in with my knife she freaked out, and even to this day I have no clue where she is.
Any who, I guess I can just hide the knife in my bag for the day. I can get out of bag checking that morning. Then after school we can go to the movies, and I can stab her in the back. I'll sit behind her, we never sit next to each other normally, so it won't seem like that big of a deal. I will just ask her if we can go to the movies once we get out of school. Just so it doesn't seem like I was planning on going to the movies hours before. I hope I'm not forgetting anything please tell me if everything I planed out is good.

I don't care, as long as we kill her