(knowledge construction) practices enacted and supported in a cultural context (not isolated, disembodied skills), with explanation, evaluation, and symbolization recognized as central practices right from the start.
Finally, both design teams assumed that understanding of the core ideas of science also involves understanding their epistemology (i.e., the data patterns and knowledge construction and evaluation practices that serve to give rise to those core ideas) and that even young children would have some initial epistemological ideas that could be built on, enriched, and transformed in the course of science learning (see Chapters 3 and 6). Hence the foundational ideas used to structure the learning progressions included foundational epistemological ideas as well as the foundational domain-specific ideas previously discussed. In the case of the learning progression for evolution, those epistemological ideas were characterized as of two broad sorts: (1) ideas about forms of argument (which would be elaborated over the learning progression to include understanding of both model-based and historical arguments) and (2) knowledge of specific mathematical and representational tools that can be used to enrich one’s descriptions of nature (which would be elaborated to include the tools of measurement, data creation, representations of distributions, Venn diagrams, cladograms, etc.). In the case of the learning progression for the atomic-molecular theory, the designers focused on the elaboration of the core epistemological ideas of measurement, models, and evaluation of ideas using data and argument.
Including important foundational ideas about epistemology (to be built on and elaborated in the course of the learning progressions) is in keeping with current research findings that children have a capacity for metacognitive reflection: that is, they can ask themselves not only “What do I know?” or “What should I do?” but “How do I know?” “Why should I do it?” Furthermore, there is increasing evidence that flexible and adaptive use of practices is greatly aided by explicit understanding of the reasons for those practices. Current research also makes clear that these deeper epistemological understandings do not come for free with the mere use of practices (Roth, 2002). Rather, they require explicit reflection and discussion of these issues. Significantly, recognizing the importance of engaging students with these issues has led to changes in how the practices themselves are taught.
This work on constructing learning progressions is new, still partial and incomplete, and has not had a chance to be discussed and critiqued by the larger community. We present one example in greater detail here—work on a learning progression for matter and atomic-molecular theory—because of the somewhat larger research base in this area for K-8 students and to illustrate what such an approach might look like and how it is different from current practice. Also, this example shows how core ideas permit cross-domain integration (in this case, spanning domains as different as the physi-