3,400 Hoosier teachers have retired in the last year, and observers expect a growing wave of retirements, but they don't agree on why.

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The Indiana Public Retirement System says there were 13 percent more teacher retirements in the just-ended fiscal year, on top of a whopping 63 percent increase the year before.

The huge jump in 2011 is misleading, because 2010's retirements were unusually low, plummeting by one-third from the year before. INPRS's Jeff Hutson and Indiana State Teachers Association president Nate Schnellenberger agree many would-be retirees hung on for an extra year because of the recession. But retirements in 2011 topped 2009 levels as well.

Schnellenberger blames dissatisfaction with Governor Daniels' education reforms, especially last year's bill overhauling teacher evaluations. That bill required schools to make student test scores part of a teacher's assessment, and to make those scores worth up to a third of the formula for setting teachers' pay.

Schnellenberger says teachers don't object to performance evaluations, but says making their ratings depend on test scores is unfair. He argues even teachers who earn raises under the new system won't get much because of budget constraints.

Hutson says teaching has become more stressful since the current group of retirees entered the workforce, and says Indiana's new laws are one piece of that. But he says retirements are rising in large part because the baby boomers are reaching retirement age, and will continue to increase for the same reason.

And Hutson says some retirees may have concluded budget cuts in their district made it the right time to step away.