Moving around the room
Walking around the room not only includes the students in your lecture but will keep their attention on you. Students do not want to get caught doing other things when lecture is going on.
I've noticed that students attention span increases when you walk around the room. They are less likely to text underneath the table or try to Facebook on their computers. I have also noticed that it is easier for me to walk around the room than to stay in the same place. I tend to get really nervous when presenting material to new faces; walking around the room really releases that nervous energy and allows me to be a more effective instructor.
In bigger classes, in bigger classrooms, it is necessary to move around, as the instructor delineates the area of communication with the students. Every student in the room should be made aware that he or she is part of the communication bubble and this will keep him or her constantly alert and receptive to the lecturer.
I agree that moving around the room is great. When the instructor is walking around while talking it keep the students up and focused at all times.
