science-rich centers, industry, and other organizations must participate in professional development activities with teachers.

[See Program Standard D and System Standard D]

Some of the most powerful connections between science teaching and learning are made through thoughtful practice in field experiences, team teaching, collaborative research, or peer coaching. Field experience starts early in the preservice program and continues throughout a teaching career. Whenever possible, the context for learning to teach science should involve actual students, real student work, and outstanding curriculum materials. Trial and error in teaching situations, continual thoughtful reflection, interaction with peers, and much repetition of teaching science content combine to develop the kind of integrated understanding that characterizes expert teachers of science.

New forms of collaboration that foster integrated professional development for teachers must be developed. One promising possibility is the reorganization of teacher education institutions into a professional development school model, where practitioners and theoreticians are involved in teacher education activities in a collegial relationship. Another is extensive collaboration among schools, colleges, local industry, and other science-rich centers.

Many teachers come to learning activities with preconceptions about teaching science. At a minimum, their own science learning experiences have defined teaching for them. More accomplished teachers have their own teaching styles and strategies and their own views of learning and teaching. When teachers have the time and opportunity to describe their own views about learning and teaching, to conduct research on their own teaching, and to compare, contrast, and revise their views, they come to understand the nature of exemplary science teaching.

[See Assessments Conducted by Classroom Teachers in Chapter 5]

Learning experiences for prospective and practicing teachers must include inquiries into the questions and difficulties teachers have. Assessment is an example. Teachers must have opportunities to observe practitioners of good classroom assessment and to

review critically assessment instruments and their use. They need to have structured opportunities in aligning curriculum and assessment, in selecting and developing appropriate assessment tasks, and in analyzing and interpreting the gathered information. Teachers also need to have opportunities to collaborate with other teachers to evaluate student work—developing, refining, and applying criteria for evaluation. Practicing teachers will benefit from opportunities to participate in organized sessions for scoring open-ended assessments.

Professional development activities create opportunities for teachers to confront new and different ways of thinking; to participate in demonstrations of new and different ways of acting; to discuss, examine, critique, explore, argue, and struggle with new ideas;