The mythology surrounding the substitute teacher is not a pretty one: Paper airplanes, lost learning, bullying. But as schools collect more information about teacher absenteeism and its consequences, districts and schools are exploring ways to professionalize substitute teaching--or experiment with alternative ways of coping with teacher absences. While substitute teachers are largely seen as occasional pinch hitters for full-time teachers, statistics show that students spend a good chunk of their time in school with them. The Washington-based National Council on Teacher Quality estimates that the average teacher misses between six and 13 days of school per year. And some research now links high rates of teacher absence to lower-than-expected achievement results for students. That has led a growing number of educators to call for creating a more professionally prepared substitute-teaching workforce.