I agree with the above - different students do require different approaches. Flexibility is the very key to being an instructor. If your student doesnt respond well to one method or explaination I feel it is the instructors *duty* to adapt and to find something that *does* work for the student.
Usually, non-stop talking & yelling dont work....but everyone is different - as yet I havent found a student I have got annoyed with even.....I have a golden rule...never never argue or shout in the cockpit - take it to the ground & deal with it there...basic airmanship degrades as the conversation does!!