"Meaning business" can be considered stress management because you have your kids under control and things will start to get calm. It is a matter of breathing and staying calm. When you learn to control your breathing, you stay calm and end up calming the people around you as well. Once the student calms, then it is easier to get them back on task.
It is important to put discipline over instruction in certain situations. It is important because the students will take you more serious and will in turn be able to get back to the instruction easily. I you just jump right back into the instruction, students will not be focused and you will not be able to get work done.
