I may be in error, but I don't fret over grades in elementary school. Grades are take home evaluations so parents can know how children are performing in school and show areas that need improvement, IMO. I don't see why homeschools in some districts are required to submit grades since the parents know how the child is doing and know what improvements are needed.
Our curricula isn't traditional stuff with tests and quizzes, plus I have my children correct their answers or verbal output as we go along. I had to do Outstanding, Satisfactory, or Needs Improvement for K-2. Starting 3rd grade it is A-F. For subjects my children give great effort, participate with a good attitude, and master the material they get As. For subjects they have great effort, participate with a good attitude, may have struggles, but still show progress they get Bs. I don't allow poor effort or bad attitude, but if they had poor effort and a negative attitude against my will, they would get lower grades. They do not yet know I assign grades. I only do it because my district requires I submit grades. Around 6th or 7th grade, I plan to start more objective means of grading like written tests, online courses, or homeschool tutorial classes.