Trials in Substituting

The beginning of this three week stint provided me with an interesting experience that I was not quite expecting: I got to play substitute. It was on a Wednesday and the students had an early dismissal at 1pm, which I thought would make my day significantly easier since that meant my co-op's last class wouldn't meet. (His last class is a traditional class, but more than half of the students have IEP's and, many days, a lack of motivation.) However, this day was one where I couldn't wait to bust out the doors and drive away and maybe call in sick the next.
They had an actual substitute with me, who was actually a recent Millersville graduate, but my co-op told her I would run the show. This was easier said than done. Each class began with "Yes, a sub!" as students filed into the room and followed with attempts to bargain their way out of the small amount of in-class reading that needed to be done. After completing guided reading, students avoided doing work like the plague. Many resorted to playing games on their iPads (one of the biggest downfalls of devices in the classroom) and ignoring multiple requests to get to work. This was all expected and taken with a grain of salt. It was not until Literacy (a remedial class for mostly ESL students who have not reached reading fluency), which is usually my favorite class due to their high energy, that things went south.
These students, who are masters of time wasting but will usually comply when told to get on task, almost completely refused to do anything for me. They talked over me, were incredibly loud, were walking around, and refused to do work. One student, just as everyone was turning to the page in which we were to start, got out of his seat and sat down at a computer to check basketball scores. I told him to get off the computer and come to his seat, to which he replied, "Just a minute, Miss, I want to see who won." I sternly told him once more to get off the computer and he ignored me. I had to make the entire class wait while I walked over and closed the computer on him (which another student was now surrounding). He and the other student said that my doing so was "disrespectful", to which I retorted, "No, you guys are being disrespectful. Get in your seats." I was tense, frustrated, and defeated the rest of the period, and I think the students sensed it. Some of them took advantage of my demeanor and some of them seemed to feel the way they would if their parents were disappointed in them. After my negative report on the class to my co-op, he reprimanded a few of the students the next day, and the atmosphere in class was again tense.
I feel bad that things went the way they did and I constantly question if I handled things correctly that day. It also makes me question how I carried myself prior to being put in the position of a substitute; why was I not able to gain enough of the students' respect to have them listen? Would they have listened better to the hired substitute if it had been just her? Or would it have been worse? I'm really not sure. The sub said she thought things would have been worse if I wouldn't have been there, but I wonder if part of the problem is that the students already knew that I wasn't really a teacher. Also, I was disappointed that my co-op never prepped his students for his absence. He was absent for a meeting, so he knew that he wouldn't be there and could have told the students of his expectations for their behavior and work ethic and warned them of repercussions for misbehavior. I know my teachers in school used to tell us stuff like this all the time when they had a substitute coming in and I'm wondering why he didn't find this to be necessary.
Regardless, this was definitely a learning experience that I will not soon forget. I know that I will probably end up substitute teaching after graduation, so I am thankful for the glimpse into the reality of it, even if it was a fairly negative experience. Also, I'm going to have another shot at substituting this Wednesday and I'm hoping that things will go better this time. I don't want my last day there to be a bad one.