Teachers must provide students with an environment that is conducive to learning. If a student feels uncomfortable, unsafe, or not respected, then their chances of success in that class dramatically decrease. Also, as our society becomes more diverse, it is important that students learn to value and use diversity to the greater good. Teachers already have a number of roles in the classroom; yet, valuing diversity is one of the most important ones a teacher must fill.
(http://www.ndt-ed.org/TeachingResources/ClassroomTips/Diversity.htm)