Oftentimes research is way out ahead of the conventional wisdom. Occasionally though, common sense ends up being justified by research.

That's the case with new research on student teaching. For the first time, there is evidence that new teachers are measurably better in their first years of teaching if they were mentored by cooperating teachers with a record of raising student achievement.

How much better?

The right cooperating teacher appears to give a student teacher a six-month head start in her first year of teaching.

As designed, though, this study (from Matthew Ronfeldt and Stacey Brockman of the University of Michigan and Shanyce Campbell of the University of California Irvine) proves only that the quality of cooperating teachers and the student achievement produced by the teachers they once mentored are related. It does not prove that great cooperating teachers produce better teachers.

However, a study still in progress from CALDER is designed to eventually establish (or not) this relationship because it randomly assigns student teachers to cooperating teachers. Preliminary results from that study indicate that student teachers assigned to high-quality cooperating teachers and school placements reported a better experience. However, it'll be a few more years of data collection before we know if this more robust study confirms what we suspect to be the case, that better student teaching experiences make new teachers more effective.

In the meantime, there is no excuse for the 87 percent of teacher prep programs that have not acted on common sense by insisting that their teacher candidates work only in classrooms taught by effective teachers. We will continue to identify programs that make sure this happens.