Twenty years ago, your average teacher had 15 years of experience. That's changing. Changing demographics now put most teachers either under 30 or over 52, with the majority leaning toward the younger set, according to University of Pennsylvania professor Richard Ingersoll and UPenn doctoral student Lisa Merrill.

Such disparity has strong implications. Younger teachers, for example, are more supportive of performance pay according to a Public Agenda study. The same study shows that Baby Boomers aren't as motivated about improving pay.

So, what will the future look like? Apparently a lot of churn, as the current ranks of younger teachers turn over through unprecedented layoffs and/or more lucrative career opportunities. Younger teachers, reports Public Agenda, are almost three times as likely as older colleagues to leave the classroom for other education jobs in policy and administration.