Re: how many back talk would you take?
At times it happens that the teacher observes something and wishes to correct that, but the student is actually working on something else. Student should always listen to the teacher. ALWAYS. Even when you disagree, listen, take notice, think about it. This really polishes your judgement.
Off course the student may point out what he/she was working on so the teacher may respond to that. But I do not consider this back talk. These are moments where the student really learns: focus on what the teacher wants you to focus on and not what you want to focus on. This problem is very common I suppose.
A good method to show student what they are doing wrong is exaggeration. Many quickly recognise their error and know what to work on. Others pick up on it when teacher lets them feel the technique. Again others only need a few words to point them in the right direction. A good teacher, after a while, knows his students and acts accordingly. Or he/she incorporates the different techniques when teaching....