Sitting in the back row of her South Fayette High School economics class, Emily Cord waved off her teacher as he passed out voter-registration cards.

"I'm not 18 till June," she said.

An hour later, however, she was sitting in ECO102, Principles of Macroeconomics, at Community College of Allegheny County, with classmates beyond not just the voting age but the drinking age.

Emily is one of thousands of Pennsylvania students enrolled in both high school and college classes through the state's dual enrollment program, which pays part of the college tuition.

A state report released last month notes "extraordinary demand and interest on the part of students" in the program. Since the dual enrollment program started in the 2005-06 school year, state funding has doubled, to $10 million for the current school year.

In the 2006-07 school year, the number of participants increased 69 percent from the previous year, from 7,270 students to 12,267 students statewide.

While most students just sample a course or two, Emily is taking a full load of college classes, in addition to two high school classes.

On Tuesdays and Thursdays, she leaves high school just after second period and drives through twisty back roads to CCAC's West Hills campus. The unusual arrangement has resulted in two honor roll certificates now gracing her family's refrigerator, one from South Fayette and one from CCAC.

By the end of the year, she will have accumulated 33 college credits -- the equivalent of a full year of courses.

At first, it was "strange" taking classes with older students, she said. But these days, she comes across in class as polished and confident. She draws an "absolutely right, very good" comment from macroeconomics professor Julian Gallegos for a supply-and-demand graph that she draws on the board. Then she answers a question from a fellow student about when spring break starts.

She says that she doesn't miss the time she could be spending in high school because the CCAC arrangement offers her so much more freedom: She can work weekday hours at her hostess job at Don Pablo's, spend more time with her boyfriend of three years, who is also a CCAC student and routinely win radio contests as she drives around during the day, including a pair of Bon Jovi tickets last week.

She also takes two online classes at CCAC and gets much of her homework done during the weekday afternoons when she's not in class.

There's no reason seniors need to be chained to the high school walls, said Maureen Pedzwater, post-secondary transition coordinator for South Fayette High.

"Why have them at the school taking an elective that they really don't need or a study hall?" she said. "Let them get out. Why not let them have that opportunity?"

What drives Emily to spend most of her day outside of school is the opportunity to get a head start on college costs. She's seen friends and family struggle with tuition and student loans.

"I don't want to end up in debt," she said. "I know a lot of people who dropped out and have to pay student loans. I would hate that."

With the combination of the state grant and tuition money from her mother's job as a nurse, Emily and her family won't have to pay for any of her CCAC credits. She's saving up the money that she's earning working 25 hours a week for a new car, preferably a convertible.

She plans to spend one more year at CCAC after graduating from high school, then transfer to Robert Morris University. She eventually wants to get a master's degree in human resource management.

The idea of leaving high school to earn college credits is the sort of thinking that goes along with some of the efforts to restructure the senior year of high school, or rethink high school altogether, said Terry Orr, a professor at Bank Street College in New York City who has studied dual enrollment.

"There's a need to keep kids more engaged," she said. "Dual enrollment gives kids more chances at independence."

Currently, 263 students from Allegheny and Washington counties take classes at CCAC under the state dual enrollment grant program, which totally or partially pays for their college tuition. An additional 306 high school students are taking classes at CCAC that they pay for themselves, said CCAC spokeswoman Helen Kaiser.

Other high school students take classes at four-year institutions such as local Penn State University campuses and Robert Morris.

At CCAC, the high schoolers are often among the best students in his classes, said Mr. Gallegos, possibly because they are motivated enough to try dual enrollment in the first place. He was "shocked" to find out Emily was in high school, he said, noting that she seemed to take charge of other group members during a project last semester.

Some of the classes at CCAC have been easier than some of her high school classes, while others have been harder, said Emily. Her CCAC macroeconomics class often opens with a quiz, requiring more preparation than her high school class.

Ms. Pedzwater said she gets mixed feedback from students about whether they find the CCAC classes harder or easier than their high school classes.

But dual enrollment, she said, has value above and beyond the academics. Students aren't just mastering college material in their classes, but are also learning to buy their books, pick their classes and -- in one instance -- sweet talk a professor into opening up enrollment in a full class.

At McKeesport Area High School, dual enrollment might be the push that some students need to make a mental transition to college.

"Once they are on a college campus, they can see themselves there," said Alice Saxon, college and career outreach facilitator. "Many of our students will be first-generation college students, and so they don't have a reference of what college life is like. If they can get that little taste of college, they can see themselves furthering their education."

Some students at McKeesport take day classes at Penn State- Greater Allegheny Campus, which is within walking distance of the high school, while others take night classes at CCAC. A few find the courses too difficult and drop out, she said, but most are pleased to find the classes challenging but "doable."

At Sto-Rox High School, guidance counselor Joe Herzing also values dual enrollment for its ability to widen the curriculum. Students go to night classes at CCAC to take electives, such as economics or sociology, that aren't offered at the high school.

One student there was so enamored with her economics course at CCAC that she's now majoring in economics as a sophomore on Penn State's main campus, said Mr. Herzing.

The school ended its experiment with letting students take classes during the day because of time spent commuting back and forth, he said.

Sto-Rox doesn't offer Advanced Placement classes, said Mr. Herzing, so dual enrollment is the only way its students can start accumulating college credit while still in high school.

Even for schools that do offer AP classes, some students and teachers prefer dual enrollment, because students must pass an AP test to get credits, and colleges have varying standards for what AP scores they accept.

"I like to see the kids getting the college experience," said Mr. Herzing. "That's what it's all about."