You are not in a tough situation...you THINK you are in a tough situation.
You have week, let it go.
You will do the same exact thing, 10 years from now, when there is a week left in the school year and some kid is an a$$.
Trust me on this one, let it go.
Very good point. One thing that is unique about my future teaching position is that I will also be the FFA sponsor, so it will be important for me to create a more personal relationship with the students than the average classroom teacher. I will be spending my summers making visits to their homes, visiting them at different activities, taking the officer team to leadership training, holding meetings, etc.
I guess with all this considered, I owe my students more than just "letting it go."
I can see your point about not just letting it go. I can also see that as a student teacher you don't want your supervising teacher to come back and think you've are not capable of getting your students do the work. Do you have a department head that you can ask? I have been at the high school level for awhile now and have always thought myself to be a teacher that will try to reach students that haven't had a lot of success in the classroom. From my experience, there are students that are a little "rough" but you can tell they just need some positive feedback and positive interactions with teachers and then they will work their hearts out. These are the students that you shouldn't let down. From how I'm reading your situation and with some experience with how students think, these girls may have signed up for the class because the thought it to be an easy grade and do not want to do the work, period. To over accommodate their lack of respect for your classroom assignments is doing a disservice to the other students that are fully participating and your teaching the girls nothing about responsibility and consequences. That too is your job as a teacher.
But I don't think having a talk would be a bad idea. I would avoid making it positive or negative, just put out the facts about what their grade will be without completing the project without emotion. I think it is not out of the realm of possibility that they are playing you and don't take you too seriously. And if the do get an F, do expect to hear from the parents. It's just the way it works.