Calculating a Letter Grade with SBG

Overall I’m very pleased with the way my 1st quarter of Standards Based Grading has gone.  This last week has been the first time all year that I’ve now been getting some questions and having some problems with SBG, both with students and parents.  I don’t think it is a coincidence that this week is when 1st quarter grades were due.  Students and parents have been so trained to focus on one simple letter to summarize an entire 9 weeks of learning.  Looking at multiple pieces of data and really analyzing where and why they are “getting it” or “struggling” is going to be a tough battle.

I thought about getting away with not assigning a letter grade at all, but I knew if I did that all heck would break loose.  So I went to my original formula I had come up with before the school year.  That formula looked something like this:

My idea here was that my “Core” goals would be worth 60%, “Intermediate” goals worth 30%, and “Advanced” goals 10%.  This would basically mean that in order to pass physics you would need to master AT LEAST all of the core goals.  Seems reasonable right?  The problem I ran into as I started looking at all the data is that some of the core goals were actually tougher to master than my intermediate goals.  I might have to do some reconsidering of each goals level, or something.  Not sure about that yet.  As I calculated letter grades based on this scale I had students with Fs and Ds that had not yet mastered some of the core goals, but did have success with some of the Intermediate and Advanced.

Anyways, what I started to consider was the argument about how an F on a traditional scale is disproportionate with the rest of the grade levels.  So I made the following adjustments to my formula:

The way this works is the even if you don’t master a single goal in my class you will have a 50% on a percentage scale which is obviously still an F.  I still wanted to put more weight on the core goals and less on the advanced.  So this seemed to have solved the problem.  As I analyzed the percentages based on this formula it seemed to me to pass the “eye test.”  What I mean by that is that if I was able to subjectively give letter grades this formula better matched letters grades to what I thought students should have earned.

I’m sure this isn’t the perfect system, and ideally we could avoid the dreaded letter grades all together, but I just don’t see a way around that right now.  I wanted to have a system that could be backed up by the data, and some way I could justify a student’s grade.  For now this seems to have done the trick, however parents haven’t received Report Cards in the mail yet.  I might have to edit this post next week…



  1. danlonghurst

    I like this. I am in agreement with making 50% the “bottom,” and so did my students, and even their parents! I always make a comment like, “Now, 50% is my bottom, but that’s if you’re in class every day making even the slightest attempt. Cut every other class and i’ll make an exception to 50% being the bottom.”

    • bradwysocki

      I agree. I don’t know if this was right or not, but I didn’t even reveal my new grade formula to the students. I basically told them I looked at the number of goals you mastered compared to the number you could have. They assumed I was taking that as a straight percentage and some had like only 30% of the goals and were not happy, but I told them not to worry. I think its a long battle ahead to try and break the habit of “What’s my Grade?” But I hope in the long run it’s worth it.

      • JimG

        This was my first year with SBG and I’m really liking it, my students are too. Well that is once they learned to the advantages of the system. We had a rough patch around progress report time because the students wanted a “grade” they could see. They were all nervous as they are seniors and those transcripts were going out soon.

        We got through it and I translated the table I found online into a spreadsheet and now am able to calculate their grade after I enter their data. It really is a neat system. I agree with the bottom being a 50 because the system is skewed. For instance when I had a student absent I entered the quiz questions that week as 0 and it happened to be A skills so their score dropped about 40 points. The student was made but when I explained the issue she was satisfied. So I have revised my formula with 50 as the base. My grade scheme is here: It is compilation of several different versions to suite the requirements of my school system.

        One thing I see as an oversight in your system is the fact that you are not giving students credit for developing skills. I think this is where we really differ. You will see from my grading chart, developing skills is a big part of it and man am I happy I had it because sometimes it can take a while for students to start mastering skills. Therefore their grades are low which gives them ants in their pants.

  2. Kelly O'Shea

    I also agree that grading on a 100 point scale seems a bit excessive. I basically start from 60, though no one here ends the quarter with outstanding core skills. So in reality I start with a 70. And for the first quarter, I usually scale from a 77 or even an 80 because the number of problem-solving objectives is so small (relative to how many there will be for every other grading period in the year). I don’t want the small number of objectives to mean such a huge grade difference when considering mastery of just one of the objectives.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s