One of the themes my Education Policy Center friends and I like to harp on is how poorly most of our K-12 system does in distinguishing high-quality educators from their low-performing counterparts. And the problem is especially pronounced in low-income urban communities, where tremendous need exists for great instruction to compensate for the challenges more students bring to school.

Do we provide the top-tier teachers real opportunities for more pay, career advancement, specialization, and expanded student reach? How about this one: Do schools work to keep the highest-performing instructors at a significantly greater rate than their peers who provide 5 to 6 months less of learning per year?

Education Week guest bloggers Sydney Morris and Evan Stone (co-founders of Educators for Excellence) say teachers are not surprised to hear the answer. Whether or not you are shocked, the findings of the latest report from The New Teacher Project (TNTP) should be disturbing:

…schools rarely make a strong effort to keep these teachers despite their success—and rarely usher unsuccessful teachers out.

As a result, the best and worst teachers leave urban schools at strikingly similar rates. The nation’s 50 largest districts lose approximately 10,000 Irreplaceables each year. Meanwhile, about 40 percent of teachers with more than seven years of experience are less effective at advancing academic progress than the average first-year teacher.

Irreplaceables, you say? They wouldn’t happen to be cousins to a remarkably gifted family of costumed Supers, would they?

Not exactly. TNTP defines Irreplaceables as the top 20 percent or so of instructors, those “so successful at advancing student learning that they are nearly impossible to replace.” Yet the report found in four major urban districts that these top performers are retained at nearly the exact same rate as the lowest-performing teachers. Given the relatively recent advancements in data that allow us to accurately identify and distinguish the two groups of instructors from each other, this finding is nearly criminal.

It almost goes without saying that there are numerous obstacles to giving top-flight teachers a greater reason to keep at what they do successfully. TNTP correctly focuses on poorly-trained principals, but who also can forget union-negotiated policies, onerous bureaucratic requirements, and of course, the momentum of an established culture resistant to change.

Breakthroughs are being made in some places (like the Harrison School District near Colorado Springs), but for now they remain exceptional changes on the system’s fringes. Most Colorado school districts still provide big raises for master’s degrees, and promote or release teachers based on seniority.

Like TNTP’s momentous report The Widget Effect launched a number of well-thought-out reforms — including Colorado’s own Senate Bill 191 — I certainly hope The Irreplaceables‘ recommendations spur some similar changes. Then they would mean even more to me than an animated superhero family.