Grading is subjective. That's why we have high school grading policies. We want to remove the subjectivity.
As school districts move to standards based assessments, teachers must adapt. They must understand the difference between formative and summative evaluations and teaching: a formative assessment is intended to help students develop understanding and mastery of the material. Classwork, homework, group assignments qualify as formative. Summative assignments are intended for students to demonstrate mastery of the material. They include tests, projects, and essays.