At first glance it appears that Falls Church High School has the most overcrowded classrooms in Fairfax County. Several classes on the second floor of this aging school have as many as 60 students in stuffy, unair-conditioned rooms.

But a closer examination reveals a second teacher in each classroom -- helping students individually, taking notes on the blackboard or reviewing notes in preparation for taking over the class.

It's called team teaching, it's relatively rare in high schools, but it's nothing new: "It's been around as long as teaching itself, I guess," says Falls Church principal James Wilson, who heartily endorses the method.

The philosophy behind team teaching in Falls Church High is simple: Combine two courses that complement one another, have the same pupils in class for two consecutive periods and the result is that students are bound to get a better grasp of both subjects.

Teachers say team teaching challenges students and enables instructors to get constant feedback from partners on what is working best in the classroom.

While the method is most often seen in elementary schools, it is rarely adopted in high schools because of the complicated scheduling it entails. Wilson and his administative staff, however, say team teaching is worth the nightmares it causes every year at scheduling time.

At Falls Church High, English is the subject most commonly taught by team, usually in combination with social studies classes.

"If the students are studing Russian history in class, the English teacher tries to find Russian literature for the students to read. They basically try to integrate the whole learning experience," says Estelle Meyding, a reading resource teacher who works as an adjunct to the teaching teams.

"The teachers who participate in team teaching seem to really like it . . . and the kids definitely like these classes," Meyding says as she displays a stack of recently collected end-of-the-year ratings by students. While student assessments of classroom materials varied immensely, one thing appeared to be almost unanimous -- the students say they enjoy their team classes.

Enrollment figures confirms that team teaching is a success -- nearly 30 percent of Falls Church's 2,000 students are currently enrolled in classes taught by eight teams of teachers. Most students in team classes, according to school officials, plan to go to college and are among the top academic performers at the school.

"We have 137 students signed up for next year," Ruth Blacker says with mock exasperation. Blacker is one-half of the enormously successful Blacker and Allen team -- (George Allen, that is). The team was formed last fall for a senior class in humanities. The teachers loved it, the students say they enjoyed it and word got around.

"I don't know where we're going to put them all next year, guess we'll have to knock out a wall," Blacker says.

During a short break in the tiny teachers' lounge at Falls Church, Blacker and Allen joke about team teaching. "It's almost like being married," says Allen. "It gets pretty strange . . . like when she can tell what I'm going to say before I say it. That's how you get when you teach together for a whole year."

"I just love team teaching," says Karen Strickland, a ninth grade English teacher who is one-half of a world civilization team and who teaches several "regular" English classses. "You get a lot more done in a two-hour class. There is less time wasted on administrative things, like you don't waste time taking roll twice, getting the class settled down. I find that I often teach more in one (team class) than I do in a whole week with my regular English class."

As an example of the team approach, Stickland says that while her partner is teaching the students about history, she stands at the side blackboard and takes notes which the student copy. "I'm able to show them how to take notes at the same time they're learning about something else . . . I don't have to teach a class on note-taking."

A heavy workload is the main objection teachers have to the concept, but most team teachers say the additional work is more than balanced by the enjoyment they derive from their team classes.

"I leapt at the opportunity to come here to team teach," says Glenda Petrini, who left her teaching post at South Lake High School in Reston last fall to team-teach at Falls Church. "Every expectation I had has been more than met."