This study explores two differing perspectives of the nature of students' biological knowledge structures, conceptual frameworks, and p-prims. Students from four grade levels and from three regions of the United States were asked to explain a variety of biological phenomena. Students' responses to the interview probes were analyzed to describe 1) patterns in the nature of students' explanations across grade levels and interview probes, and 2) the consistency of students' explanations across individual interview probes and across the range of probes. The results were interpreted from both perspectives of knowledge structures. While definitive assertions supporting either perspective could not be made, each hypothesis was explored. Although the more prevalent description of student conceptions within a broader conceptual framework could not be discounted, the p-prim of need as a rationale for change was also found to offer a useful description of knowledge frameworks for this content area. The difficulties endemic to the use of biology for the study of basic knowledge structures are also discussed.

This study describes the trends in students' explanations of biological change in organisms. A total of 96 student volunteers (8 students from each of 2 nd , 5 th , 8 th , and 12 th grades from 3 localities) were interviewed individually and each student was presented a series of graphics depicting natural phenomena. Students' explanations to questions of how something occurred were assigned to one of three categories (responses addressing how something occurred, why something occurred, and 'I don't know'). While the number of responses in each category was roughly equivalent in prominence across grade levels, the majority of students were unable to offer a causal explanation of how a phenomena occurred. An unexpected phenomenon was the students' predilection to redirect the interview question so they could answer them. If asked a how question, as they were in every interview instance, 32% the students answered with a 'why' response. The way biology is taught, the structure of biology or/and how we learn it could shed some light into this phenomenon and has implications for science educators.

The F-Sort of Biology Concepts was used to assess understanding of the relationships among 37 biology concepts by five groups: Preservice secondary science teachers, in-service biology teachers with 1-3 years of teaching experience, in-service biology teachers with 5 or more years of experience, scientists in any biological science field, and college seniors majoring in biology. Data collected from the F-sort were analyzed using latent partition analysis and alpha factor analysis with additional interpretation from multidimensional scaling. The subjects were asked to think aloud as they performed the F-sort and each session was audiotaped for later analysis. These analyses indicated that the biology major and experienced secondary science teachers were separated from the scientists by a dimension based on a deep-versus-surface structure understanding of the concepts. A second axis shows that scientists are separated from other groups by a fluid-versus-fixed cognitive structure dimension. That is, both experienced teachers and scientists were found to have well-constructed and ordered cognitive structures, but scientists were much more likely to see an item having a place in two or more categories, whereas experienced teachers tended to focus on only one aspect of an item, and therefore understanding that it rightfully belonged in only one category. It appears that teachers restructure their science knowledge as they become more experienced. There is an apparent transition from poorly organized to highly organized cognitive structures for biology concepts when comparing preservice, novice, and experienced teachers, respectively. The transition does not seem to be one achieving a deeper understanding of the biology concepts or to a greater degree of integration of the concepts, but rather a transition from a fairly large, loosely organized pool of biology concepts to one which is highly structured but limited to the expectations of the established curriculum. The results have implications for the well-known conjecture that teaching helps one better understand the content being taught.

No abstract

No abstract