if people are willing to pay for grades, no wonder there's inflation

After all, 'tis a free market.

Grade inflation is hard to measure, and experts caution numbers are often misleading because standards and scales vary so widely. Different practices of "weighting" GPAs for AP work also play havoc. Still, the trend seems to be showing itself in a variety of ways.

The average high school GPA increased from 2.68 to 2.94 between 1990 and 2000, according to a federal study. Almost 23 percent of college freshmen in 2005 reported their average grade in high school was an A or better, according to a national survey by UCLA's Higher Education Research Institute. In 1975, the percentage was about half that.

GPAs reported by students on surveys when they take the SAT and ACT exams have also risen - and faster than their scores on those tests. That suggests their classroom grades aren't rising just because students are getting smarter.