Since their publication in 1996, the National Science Education Standards (NSES) have been at the center of the science education reform movement in the United States. Prior to that time, the National Science Foundation, other government agencies, and private foundations had supported the development of a plethora of curricula and approaches to instruction; these led to such R&D organizations as the Biological Sciences Curriculum Study, the Chemical Bond Approach, and the Physical Science Study Committee. However, most of these programs were developed independent of one another and without the benefit of some common framework or consensus about what students should know and be able to do in science at various grade levels
