Comment by SOTGO

I think curving has its place. One of my math professors explained that in his opinion an effective test should differentiate performance as much as possible. The top students should score very well and the bottom students should score very poorly. If all the scores are clustered near the top (>80% for example) then it's hard to tell who really mastered the material and who just muddled through. Then, once you've sorted the students you can apply an appropriate curve. He did not have pre-defined thresholds, for each exam he would evaluate when he felt like the quality of work changed from an A to an A-, A- to B+ etc. The curves were very fair; he wasn't trying to force some number of As Bs or Fs, but it did increase my stress levels not knowing in advance how well I needed to do on each exam