Overwhelmed Student Teacher

I am in a school where screaming at all students is the norm. I have a kindergarten assignment and students are humiliated and degraded in efforts to control their behavior. I was able to show some positive discipline techniques to the teacher the first week by modeling and the students had several teachers from their classes call or come into comment on what a great two days they had. However, at the end of the first week, the teacher took off and I had total control of the class. None of my usual stuff worked and there was total chaos. The kids know only green for go and scream (red) or anger for stop. There is no in between. I have done long term substitute teaching taking over k-6 for months at a time and never encountered this degree of chaos. Finally, another kindergarten teacher who was listening from the hall came in and screamed and defaced their characters and sent them into tears and then of course they were intimidated into behaving. I have 6 more weeks in this classroom. How can I control this class who understands the boundary as an anger explosion? I have to get control because I will have them a full 2.5 weeks on my own. I bought several books and they will be wonderful when I set up my own classroom, but do not apply in a pre-set up environment. I refuse to damage these little personalities any further. This is ridiculous but the whole school operates this way. You can see a teacher walking with a teary-eyed student being stopped by another teacher to ask what they did wrong and then being severely reprimanded by this teacher a second time-geez. Please help. My biggest problem is that my supervisor agrees with the intimidation and screaming.