I’m not sure they really needed a study for this, but they did one anyway. That’s what government grants are for. And while the results can be interpreted in various ways – as is almost always the case – they do warrant serious consideration.
The purpose of the study was to examine the growing literature that addresses the issue of the effects of teacher gender roles on student performance. While it would be absurd to argue that either women are naturally better teachers than men, or vice versa, the point of current research is to clarify if students of one gender will achieve more with a male or female instructor.