Widespread failure on the part of students thus indicates failure on the part of the school system. But what is the source of that failure -- is it a failure to conform to the test's definition of intelligence, a poor match between the test structure and the curriculum of the school, a failure on the part of the school to educate the child, or the child's inability to learn based upon wider social forces such as poverty and a lack of enrichment opportunities that the school cannot control? The results of these tests cannot provide answers to these questions. Standardized tests only give a rough portrait of the child's current state of learning, and they do not provide full portrait of the individual and his or...

On so-called aptitude tests like the SAT, there is no distinction between students who are bright and well-prepared and those who are truly creative thinkers, and on content-based achievement tests there is no indication of why a child has failed to learn, whether it is due to a failures with causes that are confined to the classroom, or to the wider social environment. And neither type of test reveals what types of discriminatory forces could have impacted the self-esteem and the education of the test taker.
References

Matthews, Jay. (2003, November). The bias question. The Atlantic Monthly. Retrieved November 13, 2009 at http://www.theatlantic.com/doc/200311/Matthews