Through such training, teachers develop an understanding of the quality of student work that meets specific achievement levels according to the scoring criteria. Reflection of assessment reform Advocates of assessment reform call for new measures that provide a better understanding of student achievement, especially for English language learners. By using assessment portfolios that include ELLs, school systems could reduce the number of students excluded from system-wide assessment and possibly increase the number of teachers participating in professional development activities. Lower comparability and reliability Many performance-based tests, including some portfolio systems, do not easily or meaningfully translate into a single score or set of scores. The public has become accustomed to single scores, such as those used to describe the results of standardized or norm-referenced tests.
Single scores are comparable across systems and from one year to the next.
Because some districts report the outcomes of performance-based tests in words rather than numbers, some stakeholders feel the school system is less accountable for individual students. In addition, it is difficult to implement assessment portfolios that meet the reliability requirements many school systems want. Without high inter-rater agreement figures, the usefulness of the scores as an accountability tool diminishes, because the results cannot be used to compare scores reliably between schools or over time. Difficulty ensuring standardized testing conditions Some states and districts are prevented by law from implementing performance-based assessments that include portfolios. When using portfolio assessments, performance conditions may vary, and teacher bias can affect students' performance.