Well first of all, it's an open question how closely "marks" correlate with attainment. There's an undetermined amount of random "bias" in all the marking we do.

Second, the bell curve is a statistical construct and not a representation of reality, and can therefore never be used to prove anything other than statisticians know how to manipulate statistics to generate pretty landscapes.

Third, there are reasons to believe that students may be getting smarter, or more capable. As Heather says, technology may play a role here."

Fourth, there are reasons to believe that instructors have inflated their grading in response to the need to generate positive student evaluations.

So what do you do? Recognize the irrelevancy of the bell curve 9so you don't feel your grading has to conform to this statistical construct), get rid of student evaluations, and construct others ways to more accurately reflect student attainment that is free of bias.

my .02 cents

There are other factors besides students becoming more smart that can lead to inflated IQ scores and course grades.

1) Teachers/Instructors seem to be under greater scrutiny and must be able to justify the grades given to learners.  This can result in very direct instructional techniques. If you do/learn a, b, and c, you will achieve a very high mark.  Instructors/teachers even have to provide structure for project-based problems in which students are expected to use "logic" or "higher order thinking skills" to solve an authentic problem.  The result of this can be a lot of hand-holding, but also in higher grades since students can often be given a road-map of the minimum they must do to achieve certain grades.

2) It's possible that the types of questions on standardized IQ tests become over-exposed and by the time a person actually takes an IQ test, they have been exposed to a number of similar questions.  Media outlets like bookstores and the internet make it quite easy to "practice" for an IQ test. 

3) Some teachers/instructors I've worked with believe that grades can be "positive reinforcement" for students.  Thus, slightly increasing a grade might make students work harder than if they were given a lower grade. Slightly increasing grades regularly may lead (over time) to a huge change average grades given.

4) I wonder if students today are "getting smarter" or just have different information to process.  Equally smart but knowledge based on an era (?).

These are just a few thoughts I came up with.

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- odomitorie

Interesting. Not sure about the 'not getting any smarter' argument though. The Flynn Effect appears to have been operating for at least 100 years and would seem to explain much of this change (http://en.wikipedia.org/wiki/Flynn_effect. Of course, it is possible that both course grades and IQ score inflation are the result of the same underlying mechanism and that neither tells us anything of value beyond illustrating the utter uselessness of grades/scores/marks as ways to differentiate people.