There's a few things I need to clarify
1) I'm here to ask for rates, and I'm not charging for no reasons. I just hope to get a simple camera bag out of this event.
2) the photos are taken by me. You think I don't know about the poor standards?
3) she's a teacher. I'm sure she knows what she's saying when she asked for my help, but of course I intend to talk to her about it just in case.
4) I never said I'll be the main photographer.
5) don't ask me to be more generous to my teachers. I don't mix school with work
Well this thread got you slammed hard, but I would agree with the rest that it's better not to take up this job, or perhaps introduce some photographers and you can just tag along to learn. You have to realize it's a great responsibility you are taking on this job like what other CS-ers have advised. But to your questions,
1) Simply charge her the price of the cost of the bag you want.
2) If you know your standards are poor, do something bout it. Exams are over, go out and shoot more, not necessarily gotta shoot event to learn event photography, it helps to be more familiar with your gear.
3) A teacher is not a photographer, perhaps you can recommend her to CS and check out the services offered section.
4) I recommend that you better not be.
5) The more you should not take on this job as you are still her student, and have not completed secondary education yet so try not to talk with such air of cockiness.
End of the day, your teacher can say whatever she want that she dont mind your standards etc. But if the shots turn out unsatisfactory and she mount the blame on you, there is nothing you can do but apologize and face her for another year in school. Your choice mate