A great teacher can have a huge effect on a child's life. So, unfortunately, can a bad teacher. But in education, job performance has virtually nothing to do with opportunities for advancement.
Teachers who are consistently successful with students are not given leadership roles that would allow them to reach students beyond their own classrooms, and if they don't have enough seniority, they can be let go without anyone seeming to care come layoff time. This is enormously frustrating.
I've taught for 11 years at the same high-poverty elementary school in the Los Angeles Unified School District. My fourth- and fifth-grade students arrive in my classroom with varying degrees of preparedness, but they leave with a strong set of skills and a desire to continue learning. Both their intellectual curiosity going forward and their test scores reflect what they get from my class.
I'm just one among many hardworking, high-achieving teachers in L.A. Unified and other districts. But we are at risk. A recent study by the educational nonprofit organization TNTP found that each year urban school districts are losing high-achieving teachers because they make little effort to retain them, or to push out the low achievers. The report, "The Irreplaceables: Understanding the Real Retention Crisis in America's Urban Schools," estimates that the nation's 50 largest school districts lose about 10,000 excellent teachers a year. Those teachers are extremely difficult to replace. The report estimates that it takes 11 hires by a district to yield one truly great teacher, and so it strongly behooves schools to make sure their best teachers stay.