Asynchronous Grading Calibration Exercises to Improve Graduate Teaching Assistant Grading Accuracy

Postsecondary institutions employ graduate teaching assistants (GTAs) to support STEM lecture and laboratory courses. Currently, professional development programs to ensure high-quality GTA assessment of undergraduate student work are underdeveloped, and previous studies underscore the importance of developing a long-term, course-specific intervention to reduce the grading discrepancies between GTAs and faculty. In an attempt to support GTA professional development in regards to grading accuracy, we implemented a series of asynchronous grading calibration exercises in a lower-division organic chemistry laboratory course that uses a specifications grading system. While the initial implementation of the grading calibration exercises using a completion-based model did not improve GTA grading accuracy, adjustment to a threshold-based model did. GTAs had a positive reception to the exercises, highlighting their utility in constructing feedback, recognizing misconceptions, and developing confidence in their grading abilities. These outcomes exemplify the benefits of implementing grading calibration exercises using a threshold-based model as part of GTA professional development training to ensure high-quality GTA assessment of undergraduate student work and to minimize grading discrepancies between GTAs and faculty.