As long as teachers are paid more based on seniority versus other measures of demonstrated success, districts will mask the inequitable distribution of experienced, better paid teachers across their schools. If we truly care about raising student achievement, the truth about teacher qualifications at individual schools has to come out.
MaryEllen McGuire in U.S. News and World Report on how urban children suffer from having less experienced teachers (typically less than 3 years in the classroom, i.e., untenured) because union contracts let experienced teachers choose less challenging assignments.