There is a very good book that might help her manager her class without yelling. It is called, "Try and Make Me". Also, the Conscious Discipline books are helpful at this age. Try volunteering whenever you can. It may be that a helping hand can keep things in control before she gets to the point of yelling. If the teacher is yelling specifically at your child, go to her and calmly let her know that you don't want that happening to your child. If you still have concerns, go to the administrator and express your concerns. Know one wants to be yelled at, but kindergarteners are especially sensitive.