One way is to look at the relationship between poverty gaps and discipline disparities across a number of districts. (educationnext.org)
According to the research, only two East Asian nations (Hong Kong and South Korea) and Italy have a significantly bigger poverty gap. (educationbusinessuk.net)
Math Poverty Gap (8th grade math): Scale - score difference in 2009 NAEP achievement between public school students eligible and noneligible for the National School Lunch Program. (edweek.org)