What creates a contentious debate in social studies class and who is involved?

The topic of immigration creates debate, specifically, the topic of whether or not America should have closed its borders.

Mr. Neck writes on the board again: "DEBATE: America should have closed her borders in 1900." That strikes a nerve. Several nerves. I can see kids counting backward on their fingers, trying to figure when their grandparents or great-grandparents were born, when they came to America, if they would have made the Neck Cut. When they figure out they would have been stuck in a country that hated them, or a place with no schools, or a place with no future, their hands shoot up. They beg to differ with Mr. Neck's learned opinion.