1. Why do you feel that numerical grades should be de-emphasized?
Numerical grades suggest a precision of evaluation that is just not reasonable in a subjective enterprise like grading. Even when teachers create 100-point tests with, say, 20 questions of 5 points each, how do we know that answering 70% correct indicates "passing" mastery of skills on each test. That's incredibly arbitrary, considering that every test is different and covers different material based on different classroom experiences, which is why curving grades is common practice. "This test was too hard" means that the traditional 100-point scale was inappropriate. To accommodate number grades, teachers who award letter grades for papers or projects or demonstrations had to convert those letters into numbers in order to average them, which was not the point. We try to stress accumulated mastery, in which later work is really more indicative of learning than earlier work. Why penalize a student for not performing as well at the beginning of the course as at the end? Number averaging made it difficult for us to focus on cumulative grading without elaborate mathematical formulas.
Although some of our teachers still use number grades (we do not prohibit them), others are becoming increasingly comfortable with the letter grades. You can still give a test that is scored numerically--maybe out of 100 or maybe out of 65--then assign cut-offs for letter grades based on what scores seem to indicate the different levels of mastery. If a 75 seems to warrant a B, record the B in the gradebook. For example, in my Contemporary Fiction class, I gave very precise and deep thinking quizzes on the books to reward the students for reading thoroughly. They were tough, and we determined that overall a 50% was a reasonable "passing" grade for them.
At the end of the term, look at the accumulated range of grades, focusing perhaps on the later ones since they presumably demonstrate more skills than previous ones, and determine overall what level of mastery the student ultimately attained. I don't want my students to think that an outstanding final project or performance on an exam can not show up in their final grade just because they got off to a slow start.
2. How do you calculate a GPA for your students at McCallie?
Since we do have to report a letter grade, including + or -, for a student's transcript, the GPA computation is traditional. 4 points for A, 3 for B, 2 for C. But we don't give D's and figure in a 0 for an F.