GWEN IFILL: It's likely that everyone watching has spent time in a classroom, either as a student or a teacher. At 3.1 million, school teachers make up one of the largest portions of the American work force. And because teacher turnover is very high, there are probably even more former teachers.

The NewsHour's special correspondent for education, John Merrow, has the story.

JOHN MERROW: It's graduation day for students at Montclair State University, which has one of the largest schools of education in New Jersey.

WOMAN: It gives me pleasure to state that 665 members of this class are certified and qualified to teach in the public schools of the state of New Jersey.

JOHN MERROW: These graduates are among the more than 200,000 women and men who've just completed teacher preparation programs across the country.

WOMAN: I'm trying to find a job in elementary education K-6.

MAN: So, I'm a math major. I want to become a math teacher.

WOMAN: Certified in special education. I would like a teaching job anywhere in New Jersey.

JOHN MERROW: Is this a good time to become a teacher? Salaries haven't kept up with inflation, tenure is under attack, and standardized test scores are being used to fire teachers.

Richard Ingersoll of the University of Pennsylvania says teaching attracts a certain kind of person.

RICHARD INGERSOLL, University of Pennsylvania: We have these surveys that ask people, college seniors, you know, what do you want out of a career? Is it money, is it prestige, is it security, is it problem-solving, is it intellectual challenge, is it doing good and helping people?

WOMAN: If it wasn't for the people in my schools, I would have never have graduated or been here. So I want to be in the systems to help other children.

MAN: I'm not really looking for wealth or riches or anything like that.

RICHARD INGERSOLL: It's not that they, you know, want to live on a low salary or something like that. It's that their main driver is to feel that they can make — make a difference.

JOHN MERROW: First, however, they need jobs.
If you want to be a teacher in the fall, give me a hand. If you have a teaching job in September, raise your hand.

WOMAN: Not yet.

JOHN MERROW: If you have a teaching job, raise your hand. One — one hand. Wow. Not yet? Not yet?

WOMAN: Applying. We're all applying.

JOHN MERROW: Nationwide, job prospects for teachers vary widely by state, school district and subject matter. In this part of New Jersey, jobs are hard to find. School districts surrounding Montclair told us they're receiving thousands of applications for just a few dozen teaching positions.

WOMAN: It's very competitive.

MAN: There's enough of us graduating, not enough jobs.

JOHN MERROW: This isn't new. Between 2010 and 2012, Montclair State graduated 555 elementary school teachers, but only about half have found jobs in New Jersey.

WOMAN: It's a little tough right now, but I'm hoping that I'm going to get something soon.

JOHN MERROW: If and when they do get hired, chances are at least 40 percent of them will leave teaching in the first five years. Why do they leave?

RICHARD INGERSOLL: Lots of reasons. But the biggest set of reasons has to do with the quality, the caliber of the job. It's the amount of support. It's the amount of student discipline and behavioral problems in the building. It's how much say teachers have in the decisions in the building that affect their jobs. Do they have input and voice?

And I'm sorry to say that the more poor schools, the urban schools have higher teacher turnover than do the more affluent schools and the suburban schools.

JOHN MERROW: Standing in line with all these young soon-to-be-graduates, I noticed most of them were women.

RICHARD INGERSOLL: Yes, the teaching occupation's becoming more female-dominated. It was always a female occupation. People thought that was going to decline in the last 20, 30 years, as all kinds of male-dominated occupations, professions have opened up to women. However, the opposite has happened. Teaching is becoming even more female, and we have now passed the three-quarters mark.

MAN: There's not too many elementary men in the field, unless you are a physical education, art and stuff like that.

RICHARD INGERSOLL: There's large numbers of elementary schools in which there's not a single male teacher. This is a big concern.

JOHN MERROW: But there's been a huge effort to try to recruit men.

RICHARD INGERSOLL: That has never succeeded.

JOHN MERROW: The student population is changing dramatically; 20 years ago, 65 percent of students were white, today, 49 percent.

To keep up, school districts have been recruiting minority teachers to work in high-poverty schools with large numbers of minority students.

RICHARD INGERSOLL: The numbers of minority teachers have more than doubled. But the catch is that those schools and districts often are less attractive places to work. And, as a result, minority teachers have distinctly higher quit rates than do non-minority teachers.

JOHN MERROW: So minority teachers are more likely to teach in…

RICHARD INGERSOLL: In high-minority and urban schools, yes.

JOHN MERROW: And more likely to leave teaching?

RICHARD INGERSOLL: Yes. In fact, minority teachers in affluent schools, they don't quit at any higher rates than the white teachers. No, it's — it boils down to the working conditions in these places. So the data tell us we need to start paying far more attention to the retention, not just recruitment, but also retention of minority teachers.

JOHN MERROW: And so efforts to recruit minority teachers have resulted in only a 4 percent gain over the past 25 years. The teaching force remains more than 80 percent white, and most of the new hires are young.

RICHARD INGERSOLL: And you have schools now where, you know, there's hardly any veterans around. The most senior teacher is someone in their fifth or sixth year. So from a taxpayer viewpoint, there's maybe a benefit to this.

WOMAN: We are fresh out of school, we are first-year, and they don't have to pay us as much.

RICHARD INGERSOLL: On the other hand, we — common sense tells us — and also we have research showing — that experience counts, that teaching's a complex job, there's a lot of different aspects, not just simply raising students' test scores, and that — and that you get better over time.

WOMAN: It's a struggle at first, but you just got to keep trying.

WOMAN: And I feel confident in the classmates that I have seen and in myself that we can be the change they want to see in teachers.

JOHN MERROW: So what do all these changes in teaching add up to?

RICHARD INGERSOLL: Maybe all these changes aren't so much new, as they're returning to the old patterns. So when the public school system was invented over a century ago, it was — teaching was quite explicitly and intentionally made an occupation that was women, young women. Indeed, you — when you got married, you had to quit. So it — there was a lot of transiency.

JOHN MERROW: That was then.

RICHARD INGERSOLL: That was then. Now we see that it's the nation's largest occupation. It's getting bigger all the time. It's becoming more female. And its instability is increasing.

So, maybe the data are telling that these transformations are not something new; they're returning to the old.

JOHN MERROW: So, the title of this movie is not back to the future, but forward to the past?

RICHARD INGERSOLL: It could be. It could be.

JOHN MERROW: A fair number of these newly certified teachers may yet find jobs, because school districts continue hiring right up to the beginning of the school year, even into it.

For the PBS NewsHour, I'm John Merrow, reporting from Montclair, New Jersey.