Coley, this work sounds like it's on the level of the high school advanced biology course I took that was the first part of a college prep series. There is no need at all for 11 and 12 year olds to be learning that much stuff. Plus, this teacher sounds like she's trying to fail the kids with her behavior. Both of those things add up to a recipe for utter failure for everyone. I'm glad you're going to speak with the principal ASAP.
Re: the bolded: In my first job out of college, I didn't make very much, and part of my compensation was based (quarterly) on quizzes that the manager would give me based on things that I should have learned for the quarter. For one quiz, I got an 88% and I was very disappointed by that; I thought I could do better. So basically, I got 88% of the bonus that was available to me for that quarter. My manager, however had a different viewpoint: he remarked that I did a lot better than he thought I would.
I mentioned that remark to someone who opened my eyes about what he'd done: essentially, he never had any intention that I could earn the full bonus amount, because he admittedly made a quiz that he KNEW was too hard! He was messing with my abilty for compensation, and was lying to me, and that was so not cool. The 'test' should have been designed so that I would, if I learned everything, have the ability to get the full bonus amount.
This came to mind when I read your situation, OP. All of those children should have the ability to get the best grade possible. Right now, they can't do that.
A few points I would hit with the principal:
1. Since so much emphasis is on videos, how are the videos being graded? Are they C level work? A level work? GET an answer to that. If they are C level work, then why is your son forced to watch them if he's on the A track? That is holding him back and penalizing him. If he's being forced to watch them, then they need to count toward the highest possible grade that he can achieve...an A. That is the ONLY fair way it can work.
2. Why did your son get so much flack about getting the salt to do his experiment, when the teacher was the one who assigned the experiment? Does she not know what she assigned? And stress that not only does this come from your son, but you observed it. And what you heard and witnessed doesn't give you a lot of confidence in the teacher's curriculum knowledge.
3. A research paper and powerpoint presentaton on a thoroughly different topic (as I understand it) seems like WAY too much work in order to get an A at that age. Like another pp said, an A should be on mastery of topics taught in class and meeting all of those requirements, not jumping through hoops to do extra work on your own.
4. How does the grading work for the A and B levels? If they do it, they get the grade? How picky is she being with her critique of the A work? Is it such that even after putting in all of this work, your son still wouldn't get an A? (and frankly, I'd worry that if the teacher didn't know that salt was needed for the experiment, she wouldn't even know how to grade the assignment fairly or objectively)
5. At our middle school, they have prescribed topics they have to cover. So by this teacher extending the due dates, does that mean that other parts of the curriculum are not being covered? And why is this? Why are due dates being extended, yet they're not working on the work that they need to do?
I also have a 6th grader who is very smart and loves science. If he brought home that much extra homework just to get an A (which apparently needs to be self-taught!!), I would have had a lot of issues with that. I didn't have to do that much for honors biology in high school! Reading, yes, but papers? Presentations? No.
Please keep us updated.