Contrasting grading approaches in introductory physics and quantum mechanics: The case of graduate teaching assistants

At large research universities, physics graduate teaching assistants (TAs) are often responsible for grading in courses at all levels. However, few studies have focused on TAs’ grading practices in introductory and advanced physics courses. This study was designed to investigate whether physics graduate TAs grade students in introductory physics and quantum mechanics using different criteria and if so, why they may be inclined to do so. To investigate possible discrepancies in TAs’ grading approaches in courses at different levels, we implemented a sequence of instructional activities in a TA professional development course that asked TAs to grade student solutions of introductory physics and upper-level quantum mechanics problems and explain why, if at all, their grading approaches were different or similar in the two contexts. We analyzed the differences in TAs’ grading approaches in the two contexts and discuss the reasons they provided for the differences in their grading approaches in introductory physics and quantum mechanics in individual interviews, class discussions, and written responses. We find that a majority of the TAs graded solutions to quantum mechanics problems differently than solutions to introductory physics problems. In quantum mechanics, the TAs focused more on physics concepts and reasoning and penalized students for not showing evidence of understanding. The findings of the study have implications for TA professional development programs, e.g., the importance of helping TAs think about the difficulty of a problem from an introductory students’ perspective and reflecting on the benefits of formative assessment.

Figure 1

The introductory physics problem for which the TAs created a solution and graded several student solutions.

Figure 2

For the introductory physics problem, an introductory student solution that is elaborated (ISS-E) and an introductory student solution that is brief (ISS-B).

Figure 3

The upper-level quantum mechanics problem.

Figure 4

For the quantum mechanics physics problem, a quantum mechanics student solution that is elaborated (QSS-E), and a quantum mechanics student solution that is brief (QSS-B).

Figure 5

(a) One component of a sample TA’s worksheet (transcribed) related to introductory student solution ISS-B which was part of the pregrading activity. (b) One component of a sample TA’s worksheet (transcribed) related to advanced QM student solution QSS-E which was part of the pregrading activity.

Figure 6

(a) Distribution of individual scores assigned to the elaborated solutions QSS-E (QM) versus ISS-E (Intro) in the quiz context ($p=0.307$). (b) Individual scores assigned to the elaborated solutions QSS-E (QM) versus ISS-E (Intro) in the HW context ($p=0.625$). The relative size of the bubble represents the number of TAs at a particular point.

Figure 7

(a) Distribution of individual scores assigned to the brief solutions QSS-B (QM) versus ISS-B (Intro) versus QSS-B (QM) in the quiz context ($p=0.574$). (b) Individual scores assigned to QSS-B (QM) versus ISS-B (Intro) in the HW context ($p=0.273$). The size of the bubble represents the number of TAs ($N=15$).

Figure 8

(a) Percentage of TAs who graded on solution features in the five clusters on the elaborated QM solution QSS-E in the homework and quiz context. (b) Percentage of TAs who graded on solution features in the five clusters on the elaborated introductory physics solution ISS-E in the homework context ($N=15$ TAs).

Figure 9

(a) Percentage of TAs who graded on solution features in the five clusters on the brief QM solution QSS-B in the homework and quiz context. (b) Percentage of TAs who graded on solution features in the five clusters on the brief introductory physics solution ISS-B in the homework and quiz context ($N=15$ TAs).