One of the more recent educationist fads has been learning styles: verbal, visual, kinesthetic, etcetera. These have been promulgated through universities and into elementary- and high-schools. Students are eager to identify their type, and teachers are supposed to provide instruction that matches up; to do any less is to oppress by preferring some students and their innate qualities more than others (never mind that to teach in 8+ ways would still mean that each student gets non-preferred methods 80% of the time).
Imagine you're given the task of evaluating the abilities of the individuals in a group -- perhaps in sharp-shooting -- and award ratings like A or F. You might plan a series of challenges of increasing difficulty. What should you do if these turn out to be much harder than you planned -- so that while you expected a mean success rate of 60%, it was actually 20%? An obvious solution is to multiply all scores by 3 to bring up the average. But it turns out that this (and any other linear correction) penalizes the weaker performers. Better alternatives exst.