from the population might be highly motivated; or because of excellent instruction, students from the population might have greater opportunity to learn science; or the test might be biased in some way in favor of the students. Little confidence can be placed in any of these conclusions without clear statements about the assumptions and a developed line of reasoning from the evidence to the conclusion. The level of confidence in conclusions is raised when those conducting assessments have been well trained in the process of making inferences from educational assessment data. Even then, the general public, as well as professionals, should demand open and understandable descriptions of how the inferences were made.

Teachers are in the best position to put assessment data to powerful use. In the vision of science education described by the Standards, teachers use the assessment data in many ways. Some of the ways teachers might use these data are presented in this section.

[See Teaching Standard C]

Teachers collect information about students' understanding almost continuously and make adjustments to their teaching on the basis of their interpretation of that information. They observe critical incidents in the classroom, formulate hypotheses about the causes of those incidents, question students to test their hypotheses, interpret student's responses, and adjust their teaching plans.

Teachers use assessment data to plan curricula. Some data teachers have collected themselves; other data come from external sources. The data are used to select content, activities, and examples that will be incorporated into a course of study, a module, a unit, or a lesson. Teachers use the assessment data to make judgments about

• The developmental appropriateness of the science content.

• Student interest in the content.

• The effectiveness of activities in producing the desired learning outcomes.

• The effectiveness of the selected examples.

• The understanding and abilities students must have to benefit from the selected activities and examples.

Planning for assessment is integral to instruction. Assessments embedded in the curriculum serve at least three purposes: to determine the students' initial understandings and abilities, to monitor student progress, and to collect information to grade student achievement. Assessment tasks used for those purposes reflect what students are expected to learn; elicit the full extent of students' understanding; are set in a variety of contexts; have practical, aesthetic, and heuristic value; and have meaning outside the classroom. assessment tasks also provide important clues to students about what is important to learn.