There’s a difference between measuring student achievement and assigning students grades. The way I measure student achievement and growth is rather involved; the way I grade is simple. I live in a world of A’s and B’s. I rarely give C’s, and I never give a student lower than a 70 (which is a C minus.) For more information about record keeping, please see the following blogpost: https://thewayschildrenlearnmusic.wordpress.com/2014/10/25/record-keeping/
Here are 2 rating scales I use.