Yet such transformation on a large-scale has occurred rarely, if at all (Elmore, 1996). The isolation in which teachers work—isolation from one another, as well as to the world outside their schools—hinders their ability to examine their practices against external yardsticks and learn about new practices.
States and districts have traditionally attempted to provide such experiences for teachers through professional development. But the amount of professional development that states and districts provide may be inadequate, and the quality varies widely. A national survey of teachers found that, although nearly all teachers participated in professional development in 1998, most of these activities lasted from 1 to 8 hours, or less than a full day (National Center for Education Statistics, 1999). Significantly, the survey found, teachers who spent more than 8 hours in professional development were more likely than those who spent less time in such activities to say that such learning improved their classroom teaching.
Not all professional development opportunities are equally valuable. A common format, workshops or conferences, are not considered effective in producing change in teaching practices or student learning (Fullan with Stiegelbauer, 1991). Such formats tend to be short-term events, isolated from the context in which teachers teach, with few opportunities for sustained interaction with peers or experts.
The National Partnership for Excellence and Accountability in Teaching, a consortium of organizations conducting research on teacher preparation and practice, has synthesized research on professional development and developed eight principles for effective practices (1999):