Withitness
The art of knowing what's going on in your classroom at all time
A withit teacher can see when students are not paying attention, which students can’t follow the lesson, when students are becoming restless, etc.
16 teaching rules I live by
Some of these techniques you might find useful.
When students talk out of turn and are disrupting the flow of the lesson, I look directly at them and start a loud slow count from one up five. This generally works as the students have been programmed by their Thai teachers from an early age that a full count of five is swiftly followed by something highly unpleasant.