Curving grades without creating competition among students I've recently taken a new position within a math department at a large university. The department has an official policy that in most lower-level undergraduate classes (let's say anything in the calculus sequence and below), roughly half of the students should receive A's and B's, and the other half should receive C's and below.
I tend to disagree with this policy, but being new to the department and rather inexperienced with the student population, I'd like to honor the policy for the time being. So for the first time in my teaching career, I plan to curve my class to achieve a desired distribution.
One tenet of my teaching philosophy is that I try to be as transparent with students as possible about how they will be assessed, and how their performance will translate into a letter grade. This means that if I am to institute a curve next semester, I want to be able to tell students exactly how the curve will work. Of course, I'm very worried that telling them only half of them can get A's and B's will create a very competitive environment, so students will not want to study with and help each other, so learning will suffer (in fact, I'm almost certain this will happen). This leads to my question:

How can I simultaneously

tell the students how I will assign grades,
achieve the distribution desired by the department, and
still get students to buy into working together?


Seems impossible to me - maybe it is...
One quasi-solution (which potentially strays a bit from condition 2) is to have guaranteed grade cutoffs. For example, if a student achieves an 80% in the class, she is guaranteed at least a B-, even if 75% of the class scored higher. In this scenario, the perceived effect of any curve is that it &quot;can only help and not harm.&quot; This could give students at least some sense of being in control of their own destiny and that they are not only being assessed in comparison to their peers.
The problem with this solution is that determining those grade cutoffs can be tricky at the outset. If I make them too high, then at some point in the semester it will become clear that the curve will supersede the cutoffs, and competition is likely to creep back in. If the cutoffs are too low, then I could be locked into awarding an overly generous distribution that would be frowned upon by my department.
What can I do?
I think you're onto the right approach with the idea of a curve that only helps.
Based on your description, it sounds like you are in the United States. If so, the simplest way to do this would be to compute twice:

Use the standard US metric of A=90%-100%, B=80-89%, C=70-79%, D=60-69%, F&lt;60%.
Apply the curve.
Give the student the maximum of the two grades.

If you put together examinations that are far too difficult, then you may still have a problem. No matter what, however, a curve can only do so much to save you from this mistake, however, since overly difficult exams will also tend to increase the arbitrariness of assessment.
One other thing that may help in setting the curve is a trick I learned from the professor that I TAed for while in graduate school. When determining the curve, he also included all of the students who dropped the course. In a big undergraduate course, there were always a decent number of these, and they would generally be doing worse than the students who at least stuck it out to the end. The dropping student thus generally absorbed the failing grades at the bottom of the scale (except for a few deserving cases) and took the sting out of the curve for the students working hard but struggling in the class.