One of the most common activities in which teachers engage is
assessment of students. Stiggins and Conklin (1988) estimated that
teachers spend as much as a third of their professional time in
assessment-related activities. Although teachers need a variety of
observational and problem-solving skills for effective classroom assessment
(see chapter 2 by Richard Stiggins in this volume), a
substantial portion of classroom assessment activities draws upon
teachers' skills in testing and measurement. If they do not have a firm
understanding of basic principles of measurement, teachers are more
likely to engage in unsatisfactory assessment practices. Hence, a
necessary (though by no means sufficient) requirement for effective
classroom assessment is that teachers be skilled in measurement.