Juha the Cruel wrote:
We are discussing the wrong question. Our question should now be about how grades are assigned, it should be why they are assigned.
Economics. I explain this to my students every year. Consider the following: If we agree that different students have different backgrounds, different skill sets, and different rates of learning, and we want students to master a certain quantity of material then time becomes a variable. It will take some people 10 weeks, others 15 weeks, and still others 20 weeks or more to master the topics. There's no getting around that assuming that each student puts in the same effort. Now, if you create a system where time is the constant (such as a 15 week semester), mastery becomes the variable. We have to be willing to accept that some people will not have complete mastery of the material after the alloted time. How do we deal with this? Simple, we assign a "grade" to indicate the level of "mastery" obtained.
We can create a system where mastery is the watchword and there would be no grades (everyone would master, and thus receive an "A", and therefore the "A" becomes meaningless). In such a system time is the variable and therefore, mass teaching will not work. You're pretty much forced into a one-on-one situation (e.g., master and apprentice), and that's expensive.
So, how do we adjust and compensate? Well, the first and obvious element is that students don't work at the same rates/efforts, so those at a disadvantage have to work harder/longer (which means giving up something else such as cultural offerings). We also modify the system by breaking down a large pool of knowledge (such as engineering, biology, etc.) into smaller chunks (courses) along with a pre/co-requisite system. This way we get a little more flexibility than a monolithic block, but we're still stuck with grades.