Biologists and Chinese Pre-service Biology Teachers' Understanding and Application of Evolutionary Trees
Evolutionary trees are key representations used in modern biology but are difficult for teachers and students to understand. Past efforts to improve students’ understanding of trees have included studies that report on students’ tree-thinking misconceptions and the design of classroom and laboratory activities to help students better understand trees. However, there is a lack of curriculum development informed by biologists’ use of trees as well as a lack of studies in Asia where no religious beliefs influence students’ ideas about evolution. To address these gaps in our knowledge, this dissertation examines both biologists’ and Chinese pre-service biology teachers’ understanding and use of evolutionary tree representations. More specifically, the following research questions were addressed: • What different ways are tree-shaped diagrams depicted in the papers published in 2012 and 2013 in the journal Science? • What key concepts are behind the tree-shaped diagrams published in 2012 and 2013 in the journal Science? • What are the various purposes of the tree-shaped diagrams published in 2012 and 2013 in the journal Science? • Based on recent publications that include tree-shaped diagrams, how can we model the use of evolutionary trees in the journal Science? • How are Chinese pre-service biology teachers’ understanding of evolutionary trees related to biologists’ application of trees? • What difficulties do Chinese pre-service biology teachers have in understanding evolutionary trees and how do these difficulties compare to those previously documented in other research publications? • How do features of the Chinese language reflect the difficulties students have with trees? This study was guided by the Concept-Reasoning-Mode of representation (C-R-M) model in that we collected and coded separate data about biologists’ and pre-service biology teachers’ reasoning about both the concepts (R-C) and their modes of representation (R-M) of trees. First, a model was developed to characterize biologists’ use of evolutionary trees to communicate research, based on recent research reports published in Science. Content analysis was applied to Science articles and the “model of modeling” framework was chosen to guide the development of a model with four components: “representation of trees” (R-M) refers to the ways that evolutionary trees are depicted in Science articles, “data sources” and “construction of trees” (R-C) refer to the key concepts that scientists use to construct evolutionary trees, and “reasoning with trees” (R) summarizes reasons for including evolutionary trees in research reports. The model of how biologists’ use evolutionary trees informed the next study in which Chinese pre-service biology teachers’ understanding of evolutionary trees was examined. Participants in this study were recruited from a pool of pre-service biology teachers at a Midwestern University in China. The Three-Phase Single Interview Technique (3P-SIT) was used to guide collection of data using “tree thinking” questions from the literature. The data was analyzed with open and axial coding. Difficulties with trees showed problems with chronology, cladistics, homology, homoplasy, the limitations of trees, and incorrect tree representations. Although some of these difficulties for Chinese pre-service biology teachers confirm problems previously reported in the literature, several novel difficulties were also identified, some of which stem from ambiguities in the Chinese language. These difficulties were, in turn, characterized according to the developed model of biologists’ use of evolutionary trees, and each difficulty is reported with a typical example of participants’ understanding of trees. In conclusion, the C-R-M model proved to be a useful guide for investigating both biologists’ and pre-service biology teachers’ understanding of trees. The findings of this research will benefit teaching and learning about evolutionary trees by providing the tree-thinking model as a framework to inspire teachers’ pedagogical content knowledge development as well as for guiding the development of instructional materials and assessments for the teaching of evolutionary trees. In addition, suggestions for overcoming difficulties with evolutionary tree thinking generated by this study may help address the challenges that students encounter when using evolutionary trees to communicate their knowledge of evolution.
Pelaez, Purdue University.
Evolution and Development|Science education|Curriculum development
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