Conflicting missions?

the long version

"[The papers in this book] ask whether unions affect educational productivity, most notably in terms of an impact on student achievement. They analyze how teachers union function as professional organizations concerned with the occupation of teaching, as institutional actors defending interests within a bureaucratic system of education, and as political actors wielding influence on legislation and elections. Taken as a whole, these varying perspectives do not provide readers with a simple answer to the question of whether unions help or hurt educational reform. But the book does illustrate the many dimensions of the teachers unions' role in American education..." -- p.2