Bonich, Merlina, and Porter (2012) describe churn as instability among school personnel. Anyone involved in schooling knows that education churn is a constant background noise occurring in urban schools. As the authors suggest, it is a fact of life on many school campuses.
Most important, the authors suggest churn is not included as a variable in research regarding teacher turnover and attrition.
I agree that instability among personnel (admin, staff, and teachers) is an important variable missing in research. The instability is not just teachers quitting but teachers taking on new assignments, changing the subject they teach, changing their schedule from year to year, and changing schools.
Bonich, R., Merlina, J., & Porter, A. C. (2012, April). Where teachers are treated like widgets, education suffers. Education Week, 31(27), 20-21.