their understanding of science at various levels of their study of science.
DEVELOPING SCORING RUBRICS. The process of scoring student-generated explanations requires the development of a scoring rubric. The rubric is a standard of performance for a defined population. Typically, scoring rubrics are developed by the teachers of the students in the target population. The performance standard is developed through a consensus process called "social moderation." The steps in designing a scoring rubric involve defining the performance standard for the scientifically literate adult and then deciding which elements of that standard are appropriate for students in the target population. The draft performance standard is refined by subsequent use with student performance and work. Finally, student performances with respect to the rubric are differentiated. Performances are rated satisfactory, exemplary, or inadequate. Differences in opinions about the rubric and judgments about the quality of students' responses are moderated by a group of teachers until consensus is reached for the rubric.
Because a target population has not been identified, and rubrics need to function in the communities that develop them, this section does not define a rubric. Rather the steps in developing a rubric are described.
THE PERFORMANCE OF A SCIENTIFICALLY LITERATE ADULT. Developing a scoring rubric begins with a description of the performance standard for scientifically literate adults. That performance standard is developed by a rubric development team. Members of the team write individual responses to the exercise that reflect how each believes a scientifically literate adult should respond. They also seek responses from other adults. Based on the individual responses, the team negotiates a team response that serves as the initial standard.
The team's standard is analyzed into the components of the response. In the plant-in-a-jar exercise, the components are the predictions, the information used to justify the predictions, the reasoning used to justify predictions, and the quality of the communication.
Examples of predictions from a scientifically literate adult about how long the plant can live in the jar might include (1) insufficient information to make a prediction, (2) the plant can live indefinitely, or (3) insects or disease might kill the plant. Whatever the prediction, it should be justified. For example, if the assertion is made that the information provided in the prompt is insufficient to make a prediction, then the explanation should describe what information is needed to make a prediction and how that information would be used.
[See Content Standards B, C, and D (all grade levels)]
Scientifically literate adults will rely on a range of knowledge to justify their predictions. The standard response developed by the team of teachers will include concepts from the physical, life, and earth sciences, as well as unifying concepts in science. All are applicable to making and justifying a prediction about the life of a plant in a jar, but because of the differences in emphasis, no one person would be expected to use all of them. Some concepts, such as evaporation, condensation, energy (including heat, light, chemical), energy conversions, energy transmission, chemical interactions, catalysis, conservation of mass, and dynamic equilibrium,