How does diversity in the classroom affect social studies instruction and how can educators address such diversity in the classroom?

It doesn't affect instruction (never has for me) . It is good to have diversity and it is a normal state of affairs to have a diverse population in the classroom or society. If I have a foreign exchange student I will ask him/her a question or view on an issue. In my college classes at the end of the semester I would ask the students to bring a dish from their culture to share. I also taught diversity in my history lesson through pointing out the false information in books concerning discrimination and populations. In some textbooks the WW2 gets one chapter and within that one paragraph about the 6 million Hitler put in concentration camps and murdered. The same goes for slavery and Native Americans history. We need to know history good, bad, or ugly otherwise we are doomed to repeat it.