It is particularly important to identify and address issues of fairness and equity in educational contexts as academic performance can have large impacts on the types of opportunities that are made available to students. While it is always the hope that educators approach student assessment with these issues in mind, there are a number of factors that likely impact how a teacher approaches the scoring of student work. Particularly in cases where the assessment of student work requires subjective judgment, as in the case of open-ended answers and essays, contextual information such as how the student has performed in the past, general perceptions of the student, and even other external factors such as fatigue may all influence how a teacher approaches assessment. While such factors exist, however, it is not always clear how these may introduce bias, nor is it clear whether such bias poses measurable risks to fairness and equity. In this paper, we examine these factors in the context of the assessment of student answers to open response questions from middle school mathematics learners. We observe how several factors such as context and fatigue correlate with teacher-assigned grades and discuss how learning systems may support fair assessment. [This paper was published in: "Proceedings of the 30th International Conference on Computers in Education," edited by S. Iyer et al., Asia-Pacific Society for Computers in Education, 2022.]