In my AP US History class, my teacher is very strong in his complete rejection of passive voice. Although he has been teaching the use of active voice all year, now he has increased his efforts at eradicating passive voice from all of his students' essays; every instance of it is marked and corrected.
I realize that most of the time active voice is preferable. But sometimes, I find that a sentence would be written far better with passive voice. Also, in the high-pace writing experience of a timed essay, one has little ability to maintain a perfect style. I'm not really looking to dispute my teacher (writing style surely must be a fairly subjective topic), but rather to affirm how worried I should be about my occasional perfunctory use of passive voice.
So my question is this: is it really necessary to only use active voice? To what extent is this element of style, and others, influential in the official grading of AP essays?
Thanks very much for any insight this thread may provide.