title: Introductory biology students' conceptual models and explanations of the origin of variation.
abstract: Mutation is the key molecular mechanism generating phenotypic variation, which is the basis for evolution. In an introductory biology course, we used a model-based pedagogy that enabled students to integrate their understanding of genetics and evolution within multiple case studies. We used student-generated conceptual models to assess understanding of the origin of variation. By midterm, only a small percentage of students articulated complete and accurate representations of the origin of variation in their models. Targeted feedback was offered through activities requiring students to critically evaluate peers' models. At semester's end, a substantial proportion of students significantly improved their representation of how variation arises (though one-third still did not include mutation in their models). Students' written explanations of the origin of variation were mostly consistent with their models, although less effective than models in conveying mechanistic reasoning. This study contributes evidence that articulating the genetic origin of variation is particularly challenging for learners and may require multiple cycles of instruction, assessment, and feedback. To support meaningful learning of the origin of variation, we advocate instruction that explicitly integrates multiple scales of biological organization, assessment that promotes and reveals mechanistic and causal reasoning, and practice with explanatory models with formative feedback.
authors.affiliation: *Biology Department, Saint Louis University, St. Louis, MO 63103 espeth@slu.edu.
authors.forename: Elena Bray
authors.initials: EB
authors.lastname: Speth
authors.affiliation: School of Medicine, Saint Louis University, St. Louis, MO 63104.
authors.forename: Neil
authors.initials: N
authors.lastname: Shaw
authors.affiliation: Department of Biological Sciences, North Dakota State University, Fargo, ND 58108.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Momsen
authors.affiliation: *Biology Department, Saint Louis University, St. Louis, MO 63103.
authors.forename: Adam
authors.initials: A
authors.lastname: Reinagel
authors.affiliation: Biology Department, Southern Illinois University-Edwardsville, Edwardsville, IL 62026.
authors.forename: Paul
authors.initials: P
authors.lastname: Le
authors.affiliation: *Biology Department, Saint Louis University, St. Louis, MO 63103.
authors.forename: Ranya
authors.initials: R
authors.lastname: Taqieddin
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, MI 48824.
authors.forename: Tammy
authors.initials: T
authors.lastname: Long
mesh_terms: D001695:Biology / Q000193:education*; D004521:Educational Measurement; D014644:Genetic Variation; D006801:Humans; D017145:Models, Educational; D009154:Mutation / Q000235:genetics; D013334:Students; D013997:Time Factors