the theory of relativity, the atomic theory of matter, or the germ theory of diseaseâ€”as well as failures such as crystalline sphere astronomy or theories of spontaneous generation.
Science education does not always fully address the extent of change in science knowledge and practice, and this is one of the reasons why there are ongoing tensions between the way science is conducted and the way science is taught, in Duschlâ€™s view. As is noted in Taking Science to School, for example, argument is central to science but rare in classrooms. Teaching tends to focus on what students will need to recall, rather than on model-based reasoning about observed phenomena. The norms of the K-12 classroom, where answers are typically provided by teachers and textbooks, are at odds with the way scientists conduct their work, which entails painstakingly building scientific models from accumulating evidence. Curricula and standards that are incoherent and unfocused, and that vary from state to state, work against the logical development of understanding, he said. The demands of the marketplace lead commercial textbook and curriculum developers to focus on stand-alone modules that can be useful in a variety of contexts, rather than on coherent progressions of learning.
Still drawing on Taking Science to School, Duschl stressed the importance of teaching the practices of science and engaging students in the kinds of activities in which scientists engage. Doing so means allowing students to design and conduct empirical investigations, linking the investigations to the core knowledge students are developing, working from a curriculum that is linked to meaningful problems, and providing frequent opportunities for students to engage in logical arguments as they learn to build and refine explanations for their observations. Table 3-1 illustrates the relationships among the categories of empirical reasoning students need to develop, scientific practices, and the actions involved in those practices.
Currently, science education does not reflect this approach, Duschl said. Taking Science to School found that current curricula and standards:
• contain too many disconnected topics of equal priority,
• use declarative “what we knowâ€ language that does not make clear what it means to understand and use knowledge,
• tend to divorce science content from practices, and
• are not sequenced in ways that reflect what is known about the cumulative development of childrenâ€™s scientific understandings.
In contrast, the report advocates a move to the use of learning progressions (National Research Council, 2007). Learning progressions are descriptions of the way students’ understanding in a particular discipline