Students reify visually depicted cladogram relationships, and understanding cladograms as subsets of the complete Tree of Life may be the fundamental difficulty in acquiring tree-thinking expertise¶

Claim · All claims
Evidence · 1 study (2 entries) · causal r1–r2 · q2
Currency · newest study 2016 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? The authors hypothesize that understanding that any specific cladogram is a subset of the complete, unimaginably large ToL may be the fundamental difficulty students must overcome. → Laura R. Novick and Kefyn M. Catley 2016 q2 i? On the polytomy relatedness question, nearly all students who answered incorrectly chose the answer driven by visual level adjacency rather than MRCA reasoning. → Laura R. Novick and Kefyn M. Catley 2016 (2)

Evidence¶

Laura R. Novick and Kefyn M. Catley 2016¶

Laura R. Novick and Kefyn M. Catley. (2016). Fostering 21st-Century Evolutionary Reasoning: Teaching Tree Thinking to Introductory Biology Students. CBE—Life Sciences Education 15:ar66. https://doi.org/10.1187/cbe.15-06-0127

q2 · i? · causal · r1

Authors' hypothesis from the Discussion, based on the pattern of change scores in Table 5: the smallest increases (Δ = 0.09–0.10) were for polytomy and subsets of the ToL, which also had among the lowest posttest scores.

"we suspect that understanding that any specific cladogram is a subset of the complete, unimaginably large ToL may be the fundamental difficulty students have to overcome in acquiring tree-thinking expertise."

Laura R. Novick and Kefyn M. Catley 2016 (2)¶

Laura R. Novick and Kefyn M. Catley. (2016). Fostering 21st-Century Evolutionary Reasoning: Teaching Tree Thinking to Introductory Biology Students. CBE—Life Sciences Education 15:ar66. https://doi.org/10.1187/cbe.15-06-0127

q2 · i? · causal · r2

Error analysis of the polytomy relatedness question about rabbits, moles, and raccoons: students who erred judged moles more closely related to rabbits than to raccoons based on visual levels, reifying the depicted adjacency rather than reasoning from the MRCA.

"all of the students who got this question wrong on the posttest (96% in the business-as-usual condition, 84% in the experimental instruction condition) gave this incorrect answer."

Discussion¶

Related Claims¶

• Evolutionary sequence instruction was ineffective: nearly half of students incorrectly included autapomorphies as evidence for a relationship — related
• Business-as-usual students who completed the phylogenetics laboratory gained only on some tree-thinking skills, with no increase on polytomy, inference, or subsets of the ToL — related
• A research-based tree-thinking curriculum produced significantly larger pretest-to-posttest gains than business-as-usual instruction in introductory biology — related