Over the past twenty years much has been written about the knowledge bases claimed to be needed for teaching science. Aspects of this knowledge have changed over the last 20 years because of shifts in curriculum thinking. There is sharply increasing significance for the knowledge bases for science teaching in current trends in school science education. With the development of a standards-based approach to the quality of science teaching becoming increasingly common in the Western world, and phrases such as evidence-based practice becoming the catch-cry of attempts to "measure" such...