I've been power teaching in an elementary school, and while it does take a little longer for students (and my co-teacher) to grasp it, its finally working for me. I just hope they haven't forgotten it all over winter break!

I use the following in disruptive situations.
Teacher: "class", Students: "Yes" To get their attention and if they are still disruptive I choose one (disruptive) student to come to the top of the class and they lead the class in reciting the class rules.
Leader "Lets review the rules so we don't forget" (some leaders put on funny or deep voices and students answering have to mimic it)
All students "Here we go" (clap clap)
Leader "Rule 1"
All students "Listen when Teacher is talking"
Etc.etc listing off whatever the rules are in your classroom.
It does work to stop them talking, and they have no excuse if they break a rule in class.
We also use the 'hands and eyes' attention grabber, (hands clasped together and eyes on the teacher) especially when they are about to play a game and can't sit still to hear the instructions!
Good luck with it, its worth it if you put the effort in.