Any evaluation of teachers or schools that is based solely on test scores will present a dangerously inaccurate picture. Students who walk through the front door of different schools have vastly different backgrounds and abilities. We know, for example, that the education and income of a student’s parents have a significant impact on achievement, regardless of what school he or she attends. The statistic that we’re missing in this case happens to be the only one that matters for our purposes: How much of a student’s performance, good or bad, can be attributed to what happens inside the school
...more
