madbanana's Dream 2 or "Dream 5"
I have to say Wynd is a first-rate dream analyst. I think she easily rivals Freud, who is an overrated hotshot (though I do have respect for his Totem and Taboo). To add to Wynd's analysis, I'd say that the ultimate anxiety over an enemy's actions is that they'd do something that you couldn't fix or turn back (in the adult world, maybe the enemy leads to your being fired from a job). In adolescence it's really important (even though we like to think that it's really not that important at all) to look good and pretty, and grape juice stains don't come out! So, perhaps the fear is that a rival will somehow damage your chance to look good, or that she'll somehow make you look bad. A white dress is kind of like a symbol of an angelic person or someone "good," so perhaps she wants to make you look bad, not in the beauty sense but in the dignity sense. Though in real life she could be harmless, the dream could reveal an anxiety that someone who hates you could do something vindictive.
The teacher keeps you from learning by tearing up your notes. So the dream covers all levels of anxiety at school: looking pretty, being good, getting a good education, being favored/not favored by a teacher or student.
I don't think anxiety dreams predict what could happen in life. They just seem to clue you in on all your worries and worst-case-scenarios.