JUDY WOODRUFF:Finally tonight: teacher-driven success stories in the classroom. That's the focus of tonight's edition of the PBS program "Need to Know."

This excerpt tells the story of an academic transformation that began with a gym teacher.

The correspondent is Jon Meacham.

JON MEACHAM:At Naperville Central, a public high school of nearly 3,000 students, educators believe exercise will not only get kids fit, but will improve learning and academic performance.

And they're putting that idea into practice for a group of students who struggle in reading and in math. At 7:45 a.m., these freshmen and sophomores start the day in the gym.

MAN:Get your heart rate up.

JON MEACHAM:The key is to get their heart rates up right before their most difficult classes.

NADLENE ALNASS,student: Right now, I'm riding the bike to get at least 20 minutes in the zone.

MAN:The whole goal is to get them at 145 to 185 beats per minute for their heart rate.

JON MEACHAM:Once Nadlene Alnass has hit her target heart rate zone, she heads to a class to improve reading comprehension.

TEACHER:Here is an example of a text-to-world connection. And this is what you will be doing in your journals.

JON MEACHAM:Then comes pre-algebra.

TEACHER:Let's look at number 21. You cross-reduce with the...

NADLENE ALNASS:I like gym in the morning, how, like, it refreshes me. Like, I don't doze off a lot. So, I focus more on to the teacher, more on the lessons, more on everything.

PAUL ZIENTARSKI,retired physical education coordinator: Hello. Hello.

JON MEACHAM:Paul Zientarski is the brains behind the program. He was the physical education coordinator here for 26 years. He says some teachers were skeptical when he first came up with the idea.

PAUL ZIENTARSKI:They were afraid that the kids would be so hyped up coming out of P.E. going into the next class that they wouldn't be able to teach them well. So, yes, skeptical, absolutely. They thought we were weird.

JON MEACHAM:But in the six years since the program began, the results speak for themselves. On average, kids who signed up for physical education directly before reading comprehension read half-a-year ahead of those who opted out of the exercise program.

And in math, the improvements were even more dramatic. Students with the benefit of P.E. before pre-algebra consistently did better, improving two to four times more than their peers on standardized tests.

It is something that Zientarski thinks other educators need to know about.

PAUL ZIENTARSKI:People are dropping P.E. because test scores are—are failing. That's not the approach. That's—that's the exact opposite of what you need to do to be successful.

JON MEACHAM:And he's not just talking about that group of students. When it comes to academics, the district of Naperville is one of the best in the state. Zientarski believes one of the key reasons is that all kids here take a fitness-based P.E. program. And now he's trying to spread that idea to other schools.

JUDY WOODRUFF:"Need to Know" airs tonight on most PBS stations.