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

Abstract

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.