With forces Ballooning, Graying, and Destabilizing, three of the seven trends discussed in a paper by Richard Ingersoll and Lisa Merrill out of the University of Pennsylvania sound like they could have been taken from this week's East coast weather report. It's not the weather they examined though, but trends in the largest workforce in the United States--teachers. Using SASS data from 1987-2008, they found the three aforementioned trends in the teacher workforce, as well as Greening, Becoming More Female, Diversifying, and Not Declining in Academic Ability. 

There has been much talk about class size increasing and teachers being laid off as district budgets have tightened in recent years. In contrast to this, the data from 1987-2008 indicate that while K-12 student enrollment increased 19 percent, the teaching force increased by a disproportionate 48 percent. Of course the SASS data do not yet reflect the economic downturn, so Ingersoll and Merrill examined more recent data from the Bureau of Labor Statistics and Common Core of Public School Data. With a net decline of 50,000 to 80,000 teachers from 2008 to 2011, these data do show a slight reversal of the Ballooning trend. However given the massive inflation of the workforce over the two decades before the downturn--a total increase of 1.3 million teachers--coupled with the fact that the teaching force increased more than twice as much as student enrollment from 1987-2008, the recent decrease is actually relatively minor in the larger context.

The teaching force has also entered a "bi-modal" age in which the teacher force is both "graying" and "greening":

The authors are quick to note though that because retirements already hit an all time high, the graying trend has mostly passed. They also highlight the connection between the ballooning and greening trends: the increase in new teachers was driven, in large part, by the increase in new hires. In 1987-88, there were around 65,000 first-year teachers. By 2007-08, that number had jumped to 200,000:

This has several implications for districts, especially those that are increasingly "destabilizing" through more and more turnover. The data indicate that 45 percent of public school teacher turnover happens at just 25 percent of the public schools. And unfortunately, these are generally the same schools that, when forced to hire because of turnover, will have to draw from a pool of less experienced candidates, who are themselves more prone to turnover. In an effort to interrupt these cyclical forces, some districts have begun creating pay scales and bonus systems that provide incentives for quality teachers, regardless of experience, to stay at the schools that need them the most.

Ingersoll and Merrill admit to raising more questions than answers in this "exploratory" report and have promised to address some of these questions when new data are released in 2013. In the meantime, policymakers, unions, and district HR departments still have much to discuss in adapting to and accommodating these new trends.

Katie Moyer

_{Source of Graphs: Seven Trends: The Transformation of the Teaching Force by Richard Ingersoll and Lisa Merrill, University of Pennsylvania and Consortium for Policy Research in Education, May 2012}