• The traditional distinctions between ''targets," "sources," and "supporters" of teacher development activities are artificial.

• The conventional view of professional development for teachers needs to shift from technical training for specific skills to opportunities for intellectual professional growth.

• The process of transforming schools requires that professional development opportunities be clearly and appropriately connected to teachers' work in the context of the school.

[See Professional Development Standard D]

PROFESSIONAL DEVELOPMENT FOR A TEACHER OF SCIENCE IS A CONTINUOUS, LIFELONG PROCESS. The understanding and abilities required to be a masterful teacher of science are not static. Science content increases and changes, and a teacher's understanding in science must keep pace. Knowledge about the process of learning is also continually developing, requiring that teachers remain informed. Further, we live in an ever-changing society, which deeply influences events in schools; social changes affect students as they come to school and affect what they need to carry away with them. In addition, teachers must be involved in the development and refinement of new approaches to teaching, assessment, and curriculum.

[See Professional Development Standard A]

Teachers of science build skills gradually, starting in their undergraduate years, where they engage in science and gain some experience in teaching. They then experience the realities of their first years in the classroom, work with other teachers, take advantage of professional development offerings, and learn from their own efforts and those of their colleagues. This gradual development has several implications—the transition between the education of prospective and practicing teachers is a case in point. The primary responsibility for the early stages of preservice education rests with colleges and universities, but it must be shared with the practice community as prospective teachers begin their clinical work. For inservice education, the practice community has the major responsibility, drawing upon the resources of higher education, science-rich centers, and the scientific community. Continuous professional development requires a gradual shift from campus to

school, accompanied by collaboration among all those engaged in professional development activities.

Because the following standards assume continuous professional development, they are not divided into standards for the education of prospective teachers and standards for the professional development of practicing teachers. Rather they are applicable to all activities and programs that occur over a teacher's career.

THE TRADITIONAL DISTINCTIONS BETWEEN "TARGETS," "SOURCES," AND "SUPPORTERS" OF TEACHER DEVELOPMENT ACTIVITIES ARE ARTIFICIAL. In the vision of science education described by the Standards, practicing teachers—traditionally the targets for professional development—have the opportunity to become