A long with her usual must-haves—guitar, chewing tobacco and a steady stream of coffee—a few new items will be on the packing list for Gretchen Wilson's tour bus this year: a pile of geometry and algebra textbooks. "All my life, I just felt that I should have finished my education," says Wilson, 33, who dropped out of school at 15, completing only the eighth grade. "I felt like I was missing something—that there was stuff other people know that I don't. And I want to know it, even if I don't need it."

So this month, as the Pocahontas, Ill., native hits the road to promote her third album, One of the Boys, she'll be pulling double duty as a student preparing for a General Educational Development test, which she hopes to take by the end of summer. Perhaps her biggest motivation? Her 6-year-old daughter Grace. "When she gets to that point and has trouble with algebra, I want to be able to say, 'Let Mommy help you,'" says Wilson. "I don't want to be ignorant in my daughter's eyes."

But it was her humble background—she grew up in a trailer park and worked as a bartender as a teenager—that helped make her a country music phenomenon three years ago, when she hit with the brash anthem "Redneck Woman." At 15, Wilson, a solid A and B student as a child, dropped out at the beginning of her freshman year of high school in Miami, where her mother and stepfather had moved, to escape, she says, from a difficult family situation. She returned to Illinois to live with a boyfriend, with the blessing of her mother, who also never finished high school. Continuing her education wasn't an option. "I had bills to pay," says Wilson.

She scraped by with waitressing and singing gigs, billed as the Kountry Kutie. After she moved to Nashville in 1996 to pursue a music career, it took her seven years to get signed by a label—but then "Redneck Woman" brought fame almost overnight. In early interviews Wilson told some reporters that she intended to get her GED someday. And about two months ago, that off-the-cuff promise popped back into her head. "I was in the shower, shaving my legs, and I got this anxiety feeling," she says. "I thought, 'Oh my God! One of these days somebody is going to say, 'So how about that GED?' And it scared me—I got panicked. Because how do I know that some little girl isn't sticking it out at school because she heard me say that? I don't want to let anyone down like that."

Joined by her 20-year-old cousin Matt Simmons, who dropped out of school his senior year, she headed to Adult Learning Center near her home in Lebanon, Tenn., where together they took an assessment test to determine how much they needed to prepare for the 7½-hour GED. It was Wilson's first exam in nearly two decades. "I remembered those little bubbles," she says. "I hated those little bubble tests!"

The sight of the country star, brow furrowed and bent over a Scantron sheet, was enough to make other students do a double take. "One girl looked through the window to the room where they were taking the test and said, 'That looks just like Gretchen Wilson,'" recalls center director Bernadine Nelson. "We just laughed and said, 'Boy, it does!'"

Wilson says she "aced" the English and reading sections of the exam, but math was a different story. "I just had to guess. I'd look at '2 rx plus d divided by c equals what?' and I didn't have the first clue."

"She was so nervous," says Nelson. Despite her limited schooling, she still placed in the 10th-grade level for math and post-high school for English. "I've been so impressed with her," says Nelson. "She's been branded as a redneck woman, but the minute she opened her mouth, you could tell that she was smart."

While she struggles to solve the mystery of math, Wilson seems to have hit on a formula for happiness in her personal life. "I've found some sort of inner peace," she says. "I'm 100 percent comfortable in my own skin today." She attributes her newfound serenity in part to learning to live without a man. (She split from Grace's dad, Mike Penner, in 2005, though she says they remain "great friends.") "I've always been the kind of woman who had a man in her life even when he was the wrong man," she says. More recently she says she has found a Mr. Right who can handle her independence. She guards his identity, saying only that he manages a bar in Nashville and used to play arena football, but does confide that he's younger by a few years. "And that bothers me!" she says with a laugh. "Something in me tells me that's a no-no."

Her No. 1 priority though is Grace, who lives with her on a 380-acre horse farm amid a community of Wilson kin transplanted from Pocahontas. "We all live there now—me and Aunt Vickie and Uncle Vern and Uncle Dennis and [cousin] Matt and [brother] Josh," she says. "People call it Wilson Mountain—you know, 'Good night, John Boy!'" Her home is a relatively modest 3,500-sq.-ft. log cabin. "I didn't move into some 20,000-sq.-ft. mansion. I still fit in with the hillbillies!"

When she's touring, family time with Grace, who is homeschooled, includes music ("She sings like a bird") and drama ("She sets up scenarios for me to act out and if I mess it up, she'll say, 'No, no, no!' I think she'll be a director"). And, now, of course, study hour. "I want to talk the local high school into letting me graduate with them," Wilson says. "I told the principal, 'You let me walk and get my diploma there, and I'll play the prom.'"