Blackboard Support suggested that I post the following into the "Blackboard Community":

What would you think of adding another calculated column to the Grade Center that could be used to adjust proportionalities of grades being averaged? Here is an example of what I mean: I not only administer our Blackboard instance at East Arkansas Community College, but also teach a full load of courses (some online). In my online courses I administer 100-point exams and 20-point lab exercises. The labs average together and are intended to count as an additional lab score. Blackboard doesn't know how to do this, so I would like to see a calculated column that can "adjust" a score from a 20-point scale to an equivalent on a 100-point scale. Before someone suggests just using percentages, that's been tried and the math doesn't work, because Blackboard calculates, it seems, using the RAW SCORES not the percentage. Lets assume four 100-point exams and eight 20-point labs. Then, using exam scores of 82, 89, 77, and 95 with "raw" lab scores of 20, 18, 16, 20, 19, 17.5, 15, and 20. The lab average would then be approximately 18.19 (90.94%). Using an Average calculated column Blackboard would produce the result of 72.24, when the intended average is 86.79. This is because Bb uses the 18.19 "exam" score to average with the other 4. It doesn't use the percentage value (which is the equivalent 100-point scale value for the lab average) that the instructor intended to be used.

This is an actual example of one of my students: Using the Grade Center calculated columns showed a final average (four exams and an average of ten labs) of 77.1 (a letter grade of "C" on our grading scale) in the Grade Center, but upon working the grades offline in a spreadsheet, with the lab average adjusted to a 100-point equivalent, made, the student actually had a 92 average (a letter grade of "A"). That's a two letter grade error! Most instructors will take the Grade Center calculations at face value and will report grades based upon those results. The most dedicated and driven students will check their averages and compute them themselves notice the differences and proceed to file grievances against the instructor.

I devised a simple work-around, creating a general column in the Grade Center and manually entered the adjusted equivalent scores (percentages from the secondary display format as "raw" scores in the new column) and used that column in my calculations, but not all instructors are comfortable with the math and are dependent upon the technology that we provide. So, I have requested a product enhancement to give us a new calculated column capable of doing this automatically. I will now, also institute training to explain how calculated columns work, so our faculty will know what to expect and how to make the corrections, until the new feature can be brought on line.

Hi Allen,

I was pretty sure there's a way to setup the grade center how you're describing so I attempted to replicate your example in a test course.

I added 4 exams worth 100pts each and 8 labs worth 20pts each and filled them out with the scores in your example.

I created an Average column called "Lab avg" which included the 8 lab columns and got 18.19 (90.94%) like you said.

Then I created another Average column called "final avg" which included the 4 exam columns plus the Lab avg column and got 86.79% which is the expected result, right?

Screenshot:

It sounds like your final average column may have been set to display points instead of percent which isn't very useful for average columns. When creating a new average column, it defaults to percentage view so I'm not sure why that would have been changed.