Fostering 21st-Century Evolutionary Reasoning: Teaching Tree Thinking to Introductory Biology Students

Abstract

The ability to interpret and reason from Tree of Life diagrams is a vital aspect of 21st-century science literacy. This article reports the development, implementation, and evaluation of a research-based curriculum (an instructional booklet, lectures, and laboratory) to teach such tree thinking in an undergraduate biology class for science majors.

Abstract

The ability to interpret and reason from Tree of Life (ToL) diagrams has become a vital component of science literacy in the 21st century. This article reports on the effectiveness of a research-based curriculum, including an instructional booklet, laboratory, and lectures, to teach the fundamentals of such tree thinking in an introductory biology class for science majors. We present the results of a study involving 117 undergraduates who received either our new research-based tree-thinking curriculum or business-as-usual instruction. We found greater gains in tree-thinking abilities for the experimental instruction group than for the business-as-usual group, as measured by performance on our novel assessment instrument. This was a medium size effect. These gains were observed on an unannounced test that was administered ∼5–6 weeks after the primary instruction in tree thinking. The nature of students’ postinstruction difficulties with tree thinking suggests that the critical underlying concept for acquiring expert-level competence in this area is understanding that any specific phylogenetic tree is a subset of the complete, unimaginably large ToL.