I wonder if you might consider creating a progress bar that students can see on the Dashboard of each of their courses helping them to see how much progress they've made on the assignments/requirements for that course? This would have to take into consideration the relative weight of the assignment, but not the grade. If a quiz worth 2.5% of the course grade is done, they've completed 2.5% of the course regardless of what they earned for a grade on the quiz -- it's completed.
This would be a helpful balance to the course grade that students see, since that grade is only an accurate reflection to the extent that it's matched by significant progress in the course. In other words, if a student has an A, but has only completed 5% of the course, that's helpful to see. In addition, it would be nice for students to see how much progress they've made as an encouragement.
Thanks for your consideration.