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Student writing reveals their heterogeneous thinking about the origin of genetic variation in populations

TitleStudent writing reveals their heterogeneous thinking about the origin of genetic variation in populations
Publication TypeConference Paper
Year of Publication2013
AuthorsPrevost, LB, Knight, J, Smith, MK, Urban-Lurain, M
Conference NameNational Association on Research in Science Teaching
Date Published04/2013
Conference LocationRio Grande, Puerto Rico
KeywordsAACR, allele, genetics, Lexical analysis, variation
Refereed DesignationRefereed
Full Text

Variation is a core concept of genetics which helps set the foundation for evolutionary thinking for undergraduate biology students. We investigated whether students rely on surface features or a deeper understanding of genetic variation by analyzing students’ written explanations. Constructed response assessments allow students to demonstrate their thinking in their own words. Because constructed response assessments can be more difficult to analyze than multiple choice assessments, we employed computerized lexical analysis, which has been shown to reveal student thinking about complex biology concepts. For this study, we developed a pair of constructed response items asking students to explain the origin of new alleles in animal and bacterial populations. Our results show that some students relied on surface features and did not recognize origins of new alleles common to both populations. Fewer than five percent of the responses addressed mechanisms unique to bacterial populations. We also observed that students incorrectly identified natural selection as the predominant mechanism by which new alleles arise. Coupling constructed response assessment with lexical analysis revealed that students rely on surface level features to explain genetic variation and hold heterogeneous ideas (both correct and incorrect) about variation.


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This material is based upon work supported by the National Science Foundation (DUE grants: 1438739, 1323162, 1347740, 0736952 and 1022653). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.