Sometimes some of my classes can get out of control. I don't think they get as bad as some others but they can be a little hard to control.
I had a class the other week that would just not shut-up when I am trying to present something on the board. Every time I started to talk when I was at the board someone else would start a conversation with the person they were sitting beside. I tried appealing to their better nature and whilst it worked for most of the class there were still a few that wouldn't shut-up.
Now I know of some teachers who maintain absolute silence during their classes. I'm not sure quite how they do it. I'm not that big a fan of absolute silence but maybe I start all classes next year by keeping them absolutely silent and then if I reckon they'll behave let them talk. I can't go back and change anything now I just have to deal with it as it is at the moment.