SAN FRANCISCO : A disproportionately large number of poor and minority students were not in schools for assessments this fall, complicating efforts to measure the pandemic's effects on some of the most vulnerable students, a not-for-profit company that administers standardized testing said Tuesday.Overall, NWEA's fall assessments showed elementary and middle school students have fallen measurably behind in math, while most appear to be progressing at a normal pace in reading since schools were forced to abruptly close in March and pickup online.The analysis of data from nearly 4.4 million US students in grades 3-8 represents one of the first significant measures of the pandemic's impacts on learning.But researchers at NWEA, whose MAP Growth.