Justin Garritt, a Teach for America teacher in his third year at Beechfield Elementary/Middle School, said the study could help the district and principals make hiring decisions and that he hasn't heard debate about Teach for America in his school.

"When our students come in, and we close our doors, we are not a part of that," he said. "No one knows who is Teach for America and who isn't. Once you get to the first day of school, I don't care how long you've been teaching, you're going to face the same challenges."

Garritt took an unusual route to Teach for America. He graduated from college in 2011 with a degree in physical and health education.

But shortly after college, he said, he wanted a big city and a challenge, and found that in Teach for America in Baltimore. He was drawn to math because he believed he could make a bigger impact with low-income children. He also said Teach for America allows more room for creativity.

"When I was in more traditional settings, I felt like there was a line you don't cross," he said.

Garritt's training as a physical education teacher, his students said, brings an energy that keeps them motivated.

His math classes start with warm-ups in which teams earn points for right answers. He pushes students the way a coach would a sports player, with playful taunts about whether they're performing grade-level work.

"He always adds something different, he's always bouncing around," said Taylor White, an eighth-grader at Beechfield. "I wish sometimes he had less energy because it's impossible to just sit back and chill sometimes. It's impossible to fail."

Werts taught English for one year in South Korea, another experience that students credit with helping to create an effective teaching style. The first-year teacher's classroom is calm, and lessons resemble a dialogue between friends.

"It's a good thing he went through different experiences, whereas most teachers have just been in one location," said Patrick Anselme, a junior at Paul Laurence Dunbar High School. "He knows how far I have to go to get to where Koreans are in math."

Cass pointed out that the study didn't draw any conclusions about why students of Teach for America educators performed better on math tests.

She said Teach for America educators rely on mentoring and support from colleagues from all backgrounds.

"We're starting to see that there is a false divide between alternative certification and traditional certification," she said. "Because in reality, we see excellent teachers from all backgrounds. Our feeling is that the more collaborative our work is, the better we perform."

Stone said while he respects that Teach for America educators fill voids in struggling schools, he'd like to see a reliable measure of their effectiveness.

"Organizationally, I don't know that's where we should continue to invest," Stone said.

"We need to be looking at developing stronger teachers who stick around," he said. "And I don't think anyone should be learning their job at the expense of the students who are sitting in their class."