In 2008, the nation suffered an extremely deep recession, the worst since the great depression of 1929. College graduates found few jobs awaiting them and many turned to the more stable but relatively low paying teaching profession as a stopgap. Alternative programs such as "Teach For America" (TFA) and for laid off professionals there were the "Teaching Fellows" (TF) programs that funneled them into the teaching profession. Many school districts offered retirement incentives to encourage higher salaried teachers to retire. The result was that school districts across the country saw a turnover of their teaching staff. However, the teacher turnover had a big downside, the constant teacher turnover hurt student outcomes.
The picture above shows how unstable the teaching profession became, starting in the mid 2000s. In the 1980s, most teachers viewed teaching as a life-long profession and most teachers had fifteen years of experience, were vested, and looked forward to receiving a pension. However, by the 2000s that changed dramatically, the largest group of teachers only has one year in the profession, not vested, and the majority will not be teaching before they are even vested! For New York City teachers, 55% of the teachers have left the profession before they actually make it to ten years in 2012 and in 2013, as the recession started to ease, the number of teachers leaving the profession are increasing.
The constant teacher turnover, with inexperienced teachers, many of them not fully certified and subject to a steep learning curve themselves, destabilizes the schools and hurt student academic achievement. Why the media and politicians chose to ignore this just shows that its not what's best for the students but what is best for their ideological allies that counts.