It's a good start
And I am referring to the composition, the plot is very good.
My first comment is on your consistency. I noticed that in some parts, you use great shading, background detail, etc., yet in others the buildings are just squares, and the characters are only outlined. You should find the time to put the kind of detail that you put into Cybil's face or the front of the school into the entire piece. I also noticed that when a character is talking from a profile view, his or her jaw moves, yet at no other time do you do this, making that movement seem very awkward. Try to stick to one style of animation.
My second comment is that some voices are not natural. Cybil's roommate (Aubrey? Audrey?) seemed to be narrating rather than seriously discussing the escape plans, and other characters such as the friends and teacher, in instances, did not really seem to put the emotion of the situation into their voices. Try practicing each section a bit before doing a final recording.
I commend you for the time put into this, good work!