Teaching to the test isn't the same as teaching
Yeah, who knew? Scott E. Carrell and James E. West in the Journal of Political Economy (PDF), the abstract:
In primary and secondary education, measures of teacher quality are often based on contemporaneous student performance on standardized achievement tests. In the postsecondary environment, scores on student evaluations of professors are typically used to measure teaching quality. We possess unique data that allow us to measure relative student performance in mandatory follow-on classes. We compare metrics that capture these three different notions of instructional quality and present evidence that professors who excel at promoting contemporaneous student achievement teach in ways that improve their student evaluations but harm the follow-on achievement of their students in more advanced classes.
In other words, when professors teach to the test (or the student evaluations), students do worse in future courses. So, our educational system has incentivized the teachers to make the students stupid.
It's a lot like the empty calories of HFCS versus real food, isn't it?
NOTE Hat tip, GF Brandenburg.