There has been a running argument in academic circles about whether the quality of teaching has an impact on student performance in class and in follow-on courses. The problem with settling the question has been in conducting a test free of such mitigating influences as when students can pick their teacher. Researchers from UC Davis and the U. S. Air Force Academy recently took a stab at the question by evaluating Academy students who were randomly assigned to professors. Faculty members there all teach the same course using an identical syllabus and give the same exams during a common testing period. USAFA students are also randomly assigned to numerous follow-on courses.

Surprisingly, researchers found that professors who excel at promoting student achievement in the class they teach will, on average, harm the subsequent performance of their students in more advanced classes. And a professor's academic rank, teaching experience, and degree status negatively correlated with student performance in the class they taught, but positively correlated with performance in follow-on courses. Students of less-experienced instructors who did not possess a Ph.D. performed significantly better in the contemporaneous course, but worse in follow-on related courses.

The reason for this behavior? Well, the researchers aren't entirely sure why. They speculate that one potential explanation is that less-experienced professors may teach more strictly to the regimented curriculum being tested, while the more-experienced professors broaden the curriculum and produce students with a deeper understanding of the material.