teachers should teach and students should learn. When students engage in assessments, they should learn from those assessments.
Furthermore, assessments have become more sophisticated and varied as they have focused on higher-order skills. Rather than simply checking whether students have memorized certain items of information, new assessments probe for students understanding, reasoning, and use of that knowledge—the skills that are developed through inquiry. A particular challenge to teachers is to communicate to parents and policy makers the advantages of new assessment methods.
Assessments can be done in many different ways. Besides conventional paper and pencil tests, assessments might include performances, portfolios, interviews, investigative reports, or written essays. They need to be developmentally appropriate, set in contexts familiar to students, and as free from bias as possible. At the district, state, and national levels, assessments need to involve teachers in their design and administration, have well-thought-out goals, and reach representative groups to avoid sampling bias.
Assessments also need to measure the opportunity of students to learn science. Such assessments might measure teachers' professional knowledge, the time available to teach science, and the resources available to students. Although difficult, such evaluations are a critical part of the Standards.
The science content standards outline what students should know, understand, and be able to do in the natural sciences over the course of K-12 education. They are divided into eight categories:
Unifying concepts and processes in science.
Science as inquiry.
Earth and space science.
Science and technology.
Science in personal and social perspective.
History and nature of science.
The first category is presented for all grade levels, because the understandings and abilities associated with these concepts need to be developed throughout a student's educational experiences. The other seven categories are clustered for grade levels K-4, 5–8, and 9–12.
Each content standard states that as a result of activities provided for all students in those grade levels, the content of the standard is to be understood or certain abilities are to be developed. The standards refer to broad areas of content, such as objects in the sky, the interdependence of organisms, or the nature of scientific knowledge. Following each standard is a discussion of how students can learn that material, but these discussions are illustrative, not proscriptive. Similarly, the discussion of each standard concludes with a guide to the fundamental