I know usually you're parents say something like: "You'll meet a new friend, don't worry sweetie/(whatevernickanmetheycallyou) But I have a few options if she transfers
Got a computer AND a webcam? Webcam on Skype! Keep in touch!
Keep a scrapbook of you're memories.
Try to make a long-term friendship, as some people say, friendship never ends!
Don't fret, calm down, and take a deep breath. Tell her its kerdonkers to move just because of a teacher, don't let that teacher bring her down!
I'm sorry I'm only 9-10 so I 'm not good at advice, hope I helped!