Iterative Drawing Reveals Diversity and Change in Student Thinking About Evolution

One theoretical framework for learning is that knowledge exists in pieces. Understanding emerges by developing a coherent and stable integration of multiple ideas. When learning gains are evaluated iteratively, over time, it is clear that the mental constructs representing key ideas are dynamic. Here we describe an assessment framework that enables estimation of the dynamic nature of mental constructs as students make gains towards coherency of knowledge and understanding. The framework emphasizes the value of iterative assessment combined with multivariate methods borrowed from ecology for revealing and following gains in student thinking. We applied our framework for monitoring and describing student gains in their abilities to visualize and describe the process of evolution. Our approach was observational. We evaluated 276 drawings and accompanying text-based descriptions of evolution generated by 102 students by implementing the same open-ended assessment question four times in two sections of an upper division evolutionary biology course during spring 2021. Based on a binary rubric of 10 key ideas, students showed evidence of gains and losses of key ideas over time, and their learning trajectories were diverse and dynamic. Our findings revealed students take a multitude of pathways to concept mastery and that they struggled to succinctly construct and communicate comprehensive evolutionary models. Based on our study, we recommend using iterative free-response assessment with an explicit rubric and multivariate non-metric dimensional scale data visualization for revealing student thinking and guiding data-driven revision of curriculum, teaching strategies, and assessment for achieving greater coherency and stability of knowledge.