State standards should be organized and elaborated in ways that clearly specify what students need to know and be able to do and how their knowledge and skills will develop over time with instruction. Learning progressions and learning performance are two strategies that states can use in organizing and elaborating their standards to guide curriculum, instruction, and assessment. Learning progressions are descriptions of successively more sophisticated ways of thinking about an idea that follow one another as students learn: they lay out in words and examples what it means to move toward more expert understanding. Learning progressions should be developed around the organizing principles of science such as evolution and kinetic molecular theory. Such organizing principles—which are sometimes referred to as the big ideas of science—are the coherent foundation for the concepts, theories, principles, and explanatory schemes for phenomena in a discipline. Organizing standards around big ideas represents a fundamental shift from the more traditional organizational structure that many states use in which standards are grouped under discrete topic headings. A potentially positive outcome of a reorganization in state standards from discrete topics to big ideas is a shift from breadth of coverage to depth of coverage around a relatively small set of foundational principles and concepts. Those principles and concepts should be the target of instruction so that they can be progressively refined, elaborated, and extended over time.
Creating learning performances is a strategy for elaborating on content standards by specifying what students should be able to do if they have achieved a standard. Learning performances might indicate that students should be able to describe phenomena, use models to explain patterns in data, construct scientific explanations, or test hypotheses. A clear understanding of how students can demonstrate that they have attained a standard allows assessment developers to create items and tasks that are directed at these skills and provides teachers with targets for instruction. This approach helps build coherence between what is taught and what is tested.
Assessment, which includes everything from classroom observations to national tests such as the National Assessment of Educational Progress, is a systematic process for gathering information about student achievement. It provides critical information for many parts of the education system, including guiding instructional decisions, holding schools accountable for meeting learning goals, and monitoring program effectiveness. Assessment is also a way that teachers, school administrators, and state and national education policy and decision makers exemplify their goals for student learning.
Although assessment can serve all of these purposes, no one assessment can do so. To support valid inferences, every assessment has to be designed specifically to serve its purpose. An assessment that is designed to provide information