Well, actually yesterday our instructor was sitting in a different classroom, and I was waiting for her in the classroom that's written in my schedule as usual. Because I saw her later when I was waiting for another class. She told me I was wrong and that other room that she was sitting in it is our actual class room.. WHAT?! So I didn't argue, I just said yeah it's my mistake :p because no matter how long you argue with teachers, it's always you're wrong and they're right. Just let it go.