SAN FRANCISCO – Teacher union leaders in San Francisco are calling on school leaders to award educators a 21 percent pay raise over the next three years so they won’t be priced out of the city’s skyrocketing housing market.

SFGate.com reports the United Educators of San Francisco’s extraordinary pay raise demands are “the first volley in what is shaping up to be contentious contract talks.”

“Our wage proposal will give teachers and (teacher aides and office workers) a fighting chance to stay in the city they love,” UESF President Dennis Kelly told the news site.

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According to union statistics, 72 percent of San Francisco teachers live in the city, down from 76 percent just a few years ago. Is it really necessary for teachers to live in the city and pay the high cost of living? That’s certainly open to debate.

Leaders of the San Francisco Unified School District say there’s no way they can meet that pay request without blowing up the district’s budget. They also refute the union’s claim that teachers are fleeing the district for better-paying jobs elsewhere. San Francisco teachers are actually quite well-paid; an average first-year educator earns $58,291 in salary and benefits, according to SFGate.com.

The unionists’ sense of entitlement is no doubt being fed by the huge, $6 billion K-12 tax hike that California voters approved in late 2012. The public school funding pie has grown, and in typical labor union fashion, UESF members are demanding a bigger slice.

But do they deserve it? They say you pay for what you get, and what are the taxpayers of San Francisco getting? The school district did not meet federal measures for Adequate Yearly Progress in academics in 2013, according to a release from SFUSD itself.

Observers expect San Francisco teachers to get some kind of pay hike as part of their next contract, but probably just a fraction of the 21 percent being demanded.

We hope someone with a basic understanding of economics explains to UESF negotiators the domino effect that a huge pay raise would likely have on the district.

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The more money the district spends on wages and benefits, the less money it will have for academic and extracurricular activities for students. San Francisco families that might already be hanging by a thread could respond to the diminished educational experience by leaving the city, which would first diminish tax revenue, then the district’s budget, and finally the number of teaching positions.

In other words, a big payday for unionized teachers could trigger a kind of financial death spiral for the district.

It’s unlikely anyone in the progressive utopia “by the bay” will listen to such a warning, but it has to be said, if for no other reason than to warn Americans about the ramifications of unchecked union greed.