It does hurt the teacher - if this is an authentic teacher. Why? Because it hurts the teaching.alwyn said:It doesn't hurt the teacher, and sometimes helps the idiots. <grin>
On the other hand there may be a possibility that a teacher gets surrounded by idiots and is pretending not to see it - just to let other students to see the idiots by themselves. But idiots always introduce noise, and no one that I know about can really work when constantly surrounded by noise. Like the field will not bear its fruits without being weeded.