  Grading can shape students' learning and encourage use of effective problem
solving practices. Teaching assistants (TAs) are often responsible for grading
student solutions and providing feedback, thus, their perceptions of grading
may impact grading practices in the physics classroom. Understanding TAs'
perceptions of grading is instrumental for curriculum developers as well as
professional development leaders interested in improving grading practices. In
order to identify TAs' perceptions of grading, we used a data collection tool
designed to elicit TAs' considerations when making grading decisions as well as
elicit possible conflicts between their stated goals and actual grading
practices. The tool was designed to explicate TAs' attitudes towards
research-based grading practices that promote effective problem solving
approaches. TAs were first asked to state their goals for grading in general.
Then, TAs graded student solutions in a simulated setting while explicating and
discussing their underlying considerations. The data collection tool was
administered at the beginning of TAs' first postgraduate teaching appointment
and again after one semester of teaching experience. We found that almost all
of the TAs stated that the purpose of grading was formative, i.e., grading
should encourage students to learn from their mistakes as well as inform the
instructor of common student difficulties. However, when making grading
decisions in a simulated setting, the majority of TAs' grading considerations
focused on correctness and they did not assign grades in a way that encourages
use of effective problem solving approaches. TAs' perceptions of grading did
not change significantly during one semester of teaching experience.
