Towards understanding how to instruct students in dichotomous identification keys in a mixed STEM forensic science education environment.


  • Trevor Stamper Purdue University
  • Lauren Weidner Arizona State University
  • Gregory Nigoghosian Department of Entomology, Purdue University
  • Nastasha Johnson
  • Cong Wang
  • Chantal Levesque-Bristol


Morphological assessment is a traditional approach to specimen identification in many forensic subdisciplines. A dichotomous key guides the user through taxa determination for a specimen by providing a series of choice nodes that center around morphological differences. Each nodal choice leads to either a new set of dichotomous choices or a taxa decision. In a forensic analysis course, we evaluated student’s ability to utilize a dichotomous key down to species for a limited set of taxa, by reviewing their nodal decisions along with their confidence level using a Likert scale (1-5). Along with individual decision recording, students conducted a post-decision group comparison, following a think-pair-share active learning model. If student answers were not the same, they re-evaluated their specimen until a mutual evidence-based decision was reached. Students displayed high decision confidence but low accuracy. We observed a higher initial accuracy from students enrolled in STEM majors when compared to non-STEM majors.  From these data we aim to improve student training in the use of dichotomous keys for species identification, with a continued approach that can be then used to provide guidelines for how forensic scientists should approach dichotomous key training.

Author Biography

Trevor Stamper, Purdue University

Clinical Assistant Professor

Department of Entomology