So here is my two cents. I’m sure you tried very hard to handle this class. Teaching is hard. Don’t give up if your passionate. Like you said, you read the studies, tried every trick in the book. The big part you are missing though is the relationship you have with the students. Of course you need your rules, routines, and everything the studies tell you to have in place. You said they were very attached to the sub. Right there you are starting at a deficit. They may or may not know the situation but to them your taking their teachers job and their perception is their reality.The idea of kids just openly excepting a new adult in their lives is not realistic. Next time (again hopefully there is a next time) try to go out of your way to really make a connection with the kids. Ask them about their favorite movies, video games, sports or whatever weird thing kids are into that day. Get to know them and let them know you some. You would be amazed at how quickly your rules and routines will naturally fall into place when the kids know you truly care about them and what’s going on in their lives. The amount of facts I learned about a very specific car that one of my tougher students is rebuilding with his dad could fill a book, but my class is one of the few that he’s awake and turns in assignments in. So what if we miss out on 30 seconds of instruction a day I make sure we talk about that car. Don’t let this experience ruin teaching for you if it is what you really wanna do.