  Physics graduate teaching assistants (TAs) are often responsible for grading.
Physics education research suggests that grading practices that place the
burden of proof for explicating the problem solving process on students can
help them develop problem solving skills and learn physics. However, TAs may
not have developed effective grading practices and may grade student solutions
in introductory and advanced courses differently. In the context of a TA
professional development course, we asked TAs to grade student solutions to
introductory physics and quantum mechanics problems and explain why their
grading approaches were different or similar in the two contexts. TAs expected
and rewarded reasoning more frequently in the QM context. Our findings suggest
that these differences may at least partly be due to the TAs not realizing that
grading can serve as a formative assessment tool and also not thinking about
the difficulty of an introductory physics problem from an introductory physics
student's perspective.
