What Am I Grading? (Part 2)

At the end of last year, I talked to another teacher about the "standards-based" grading policy.  For this, students are given a list of the things they are expected to know and be able to do by the end of the unit, and instead of putting a grade on a quiz or test, the teacher gives them a score for each standard, which gets translated into a letter grade by the end of the quarter.  This is intriguing to me because I want the students to focus on the skills and understandings of math rather than on the grades.  I also tried this method of grading a number of years ago (almost ten years, I think), but the system seemed more confusing to students since they were not entirely sure how their grade was calculated.  (I also don't recall how I made this calculation.)  Now that we have an online grading program, parents and students can track their grades on a daily basis, and I'm really not sure how to make the calculations or how to make the calculations clear to the users.

Having some system through which it is clear to students (and parents) how well they are understanding the topics is important to me, so I am thinking about how to include aspects of standards-based grading into my classes.

One thing I tried over the summer, and plan to continue this year, is having a unit outline of four to six big ideas I would like the students to learn over the course of the unit.  I'm hoping to keep the number of these to four "skills" like "identify the important features (domain, range, vertex) of quadratic functions based on their graphs and equations", and one or two practices like "construct clear critiques of possible solutions".  I'm figuring that the practices will appear across multiple units, but the skills belong in only one unit.  The idea here is to alert the students to the important information I want them to learn, to provide me with reminders about what understanding I want to check (via exit slips, short ungraded quizzes), and to cue students to self-assess their understanding.  So I'm creating a set of "sample problems" to go with each big idea, and providing space for students to monitor their understanding over the course of the unit.  I'll still give graded quizzes (and allow retakes) and a graded unit test.