Campbell’s Law (explained in chapter 1) predicts: it destroys the predictive validity of the tests themselves. Tests of performance are designed to evaluate the knowledge and ability that students have acquired in their general education. When that education becomes focused instead on developing the students’ performance on the tests, the test no longer measures what it was created to evaluate. If, for example, class time is diverted to practicing multiple choice questions that resemble those on the test (perhaps by using questions from past tests), students may attain higher test scores—but
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