Date of Award

Spring 5-2013

Degree Type

Honors College Thesis


Biological Sciences

First Advisor

Kristy Halverson

Advisor Department

Biological Sciences


It is well known that students often struggle with tree-thinking, a core aspect of evolutionary education. Scientists consider phylogenetic trees multidimensional hypotheses of evolutionary relationships. However, student view textbook diagrams as static, two-dimensional images. Physical manipulatives have been used to facilitate learning science content in areas such as genetics, but these instructional tools have not yet been tested in tree-thinking. In order to circumvent students’ tree-thinking struggles, I investigated the use of manipulative, three-dimensional tree models in an introductory biology course designed for non-science majors (n=163). Specifically my research questions included: What are the differences in tree-thinking learning gains when exposed to one of three instructional treatment groups?; How do students interact with manipulative tree models? I compared three treatment groups across three semesters: 1) control; 2) multichromatic model; and 3) monochromatic model. I used a mixed methods approach gathering data from pre/post assessments, course observations, and student reflections to measure student tree-thinking learning gains and interactions. I found that students had the highest tree-thinking learning gains when given explicit instruction tied with a multichromatic model (F(2,160)=15.608, p < 0.001). Students reported most challenges in the Control Treatment and the Monochromatic Treatment groups because they had difficulties distinguishing which branch represented which taxa when manipulating branches. The use of multiple colors aided students understanding of the major components of trees and facilitated easy distinction among the taxa represented. This investigation supports the use of manipulative models as interdisciplinary tools that provide a tangible, effective alternative for teaching abstract concepts.

Included in

Life Sciences Commons