encountered by students in learning the particular science concepts that are chosen. These important responsibilities and daily decisions regarding curriculum and assessment underscore the importance of science teachers having a solid background and understanding of the science subject matter that they teach.
Much of the responsibility for implementing the science standards rests with classroom teachers. Assessment is no exception. The Standards recognize the importance of a teacher's ongoing assessments and indicate that classroom teachers are in the position to best use assessment in powerful ways for both formative and summative purposes, including improving classroom practice, planning curricula, developing self-directed learners, reporting student progress, and investigating their own teaching practices. Teachers' participation in classroom activities, hour after hour, day after day, positions them to gain information and insight into their students' understandings, actions, interests, intentions, and motivation that would be difficult to glean from tests (Darling-Hammond, 1994; Moss, 1994, 1996). Teachers need not only to interpret the assessment-generated information, they also must use the information to adapt their teaching repertoires to the needs of their students.
The usefulness and effectiveness of formative assessment depend, in part, on the quality and saliency of the information gathered in the first place and the appropriateness and relevance of subsequent actions. The quality of the feedback rather than its existence or absence is the central point (Bangert-Downs, Kulik, Kulik, & Morgan, 1991; Sadler, 1989).
With regard to feedback, research makes the case for the use of descriptive, criterion-based feedback as opposed to numerical scoring or letter grades without clear criteria (Butler & Neuman, 1995; Cameron & Pierce, 1994; Kluger & deNisi, 1996). For example, in a study conducted by Butler (1987) with a random sampling of students, individuals completed an assessment task and then received one of three types of feedback: (a) tailored, written remarks addressing criteria they were aware of before taking the assessment, (b) grades derived from scoring of previous work, or (c) both grades and comments. Scores on two subsequent tasks increased most significantly for those who received detailed comments, while scores declined for those who received both comments and grades. For those assigned grades only, scores declined and then increased between the second and third tasks.
Butler's research is important to