Despite decades of criticism for tracking and ability grouping, the practices are thriving, reports USA Today, citing research from the Brookings Institution’s Brown Center on American Education. According to findings, between 1998 and 2009, the percentage of fourth-grade teachers using ability-based reading groups increased from 28 percent to 71 percent. Several factors have contributed to this trend, according to the researchers interviewed, including an increase in computerized instruction and accountability requirements under No Child Left Behind.