The actress who played Winnie Cooper on The Wonder Years, Danica McKellar, is a self-proclaimed math advocate for girls who might otherwise shy away from a subject that Barbie once famously described as "hard."

McKellar's math book for junior high girls, called Math Doesn't Suck: How to Survive Middle-School Math and not Break a Nail, will be at bookstores Thursday. It has the look and feel of a teen magazine, but puts heavy emphasis on fractions and pre-algebra.

Graduating summa cum laude from UCLA with a degree in mathematics, McKellar is also co-author of a published proof. She has testified before Congress on math education and served as a substitute teacher.

Each chapter includes clear explanations that make manipulating numbers sound easy. "A reciprocal of a fraction is found by flipping it upside down. If you want the reciprocal of a mixed number or a whole number, just convert it to an improper fraction, and then flip it!" or "Going back and forth between percents and decimals is very easy. All you need to do is take away the % sign, then move the decimal point two places – that's it!"

The book includes horoscopes, testimonials, cute doodles and quotes from girls. Word problems are brought to life with descriptions of lipstick, beads, cookies and similarly girly examples that might make the feminist in some women cringe. In the interview below, McKellar explains why being a math whiz and a girly girl are not mutually exclusive. Wired News spoke to her by phone from her home in Los Angeles.

Wired News: How did you decide to write a math book for young women?

Danica McKellar: There was an article written about me in the New York Times two years ago. It was July 2005. It told the story about how in between The Wonder Years and The West Wing I wrote this math paper, and it got published. After that article came out – I guess literary agents sit around reading the newspaper looking for ideas for books – all of these literary agents called my manager and said, "Danica is such a great role model for young girls, we think she should write a math book."

So I talked to some of them on the phone, and I clicked with one named Laura Nolan. She essentially said, "We want you to write a book about math, but what do you want it to be about? Who do you want it to be for?"

I had done quite a bit of research about math education when I spoke before Congress in 2000 about the importance of women in mathematics. The session of Congress was all about raising more scholarships for girls (in math) in college. I told them I felt that it's too late by (the time they get to) college. If you look the stats, girls start losing interest in math and grades start dropping in middle school. That's where you have to put the money.

So (I told) Laura Nolan I want to help middle-school girls stay interested in math and be good at it, and see it as friendly and accessible and not this scary thing. Everyone else in society tells them it's not for them. It's for nerdy white guys with pocket protectors. This is how 75 percent of all science is depicted on television.

The message they're getting instead is: It's really cool to be dumb. Look at Jessica Simpson. She's famous for being dumb. I guess it started with Marylyn Monroe, and she actually wasn't that dumb, but that's how she was perceived – and that's what got popular.

WN: Would you say you're on a mission?

McKellar: Yes. Absolutely.

WN: Did talk to any girls who have read the book about it? What kind of contact have you had with junior high school girls?

McKellar: During the process of writing the book I sent 10 girls chapters. In fact, my god-daughter – who is 12 years old, she was 11 at the time – would tell me when she thought a chapter needed a little spicing up. She'd say, "Oh, I never thought of that copycat fraction thing before."

I would send a chapter or two to two other girls, friends of the family and get comments. They really care about being involved and doing something important, like making an important contribution to the book.

WN: How much help did you get while you were writing the book?

McKellar: There was almost no help. The publisher I used is not a textbook publisher – it's a young adults' publisher. They do novels. I got comments from them sometimes, but not much.

WN: Did you look at math-education standards when you wrote this book?

McKellar: Oh, sure. (And) I talked to a lot of teachers. They all said the same thing – that things get bad in middle school. The number one subject, by far, that kids have trouble with is fractions – being able to go between fractions and the other forms of the same value, whether it's a percentage or a decimal. Or working with fractions, like in ratios and proportions. They need to be flexible with fractions and understand how to use them in word problems, or with proportions and things. There is just this total lack of understanding. All of those conversations helped me focus on the subjects I was going to teach. I wanted my book to be very conversational and feel friendly.

WN: Whose idea was it to do it in the style of a teen magazine?

McKellar: That was my idea, and it only came about six months ago.

WN: What's your favorite part of math to teach?

McKellar: The fun little proofs that you can do with algebra – they are sort of like crowd pleasers in a way. Like, the .9 repeating equaling one. It doesn't take a lot of algebra to prove that, and it's really fun. It kind of wows people. It's like they're watching magic happen right before their eyes.

WN: What's your favorite part of math to learn?

McKellar: I love infinite things. I love infinite small things. I love infinitely many small things. The basis off calculus is really fun and exciting for me.

WN: Do you work computer programmer's hours? Do you drink a lot of caffeine?

McKellar: No. I drink a lot of water though. I take yoga breaks. Every three to four hours I take a 20-minute yoga break.

WN: What helped you study in college?

McKellar: I'm the kind of person that responds strongly to a challenge. So somebody told me that if I wasn't a coffee drinker yet, by the end of college I'd have to be, because a math major is so tough I would have to stay up very late. I was going to need coffee to do that. Well, merely because they said that, I never drank coffee in college, never got addicted to it, never needed it. That's the stubborn side of my personality – which I try to use for good.

WN: Do you have any geeky hobbies?

McKellar: I do voices. I'm the voice in a few video games. I do one right now called Alpha Protocol. I play this character called "handler." She's like this secret spy woman. It's really cool. I was Jubilee in X-men legends. I was also in one called EverQuest 2.

WN: There are a lot of references to baking cookies, expensive clothing, cosmetics and accessories. This could be viewed as fun – or reinforcing gender roles.

McKellar: What do you think? If I'm teaching girls that do love to make cookies and do love fashion – that they can use math as a part of that – you think that's me saying, come on girls you belong in the kitchen, you belong shopping? Or, do you think it's me showing them how math is part of all their life, even the part they thought it had nothing to do with?

In the introduction and other places in the book, I reinforce the idea it's OK to be girly. It's fun to be girly and being smart is part of who you want to be. Picture yourself clicking down Wall Street in your heels with your designer bag, and you're going to need a really great job to support that shopping habit of yours, aren't you? Well, yes.

And yeah, when you go home, might you make cookies? Sure. Why not? You might be celebrating something. Maybe you'll have kids too and you might want to make some cookies for them. Maybe you are going to cut the recipe by three quarters. And guess what, you're going to know how to do that – along with managing portfolios on Wall Street.

WN: You don't think that there are so many mentions of expensive shoes and expensive purses that it's encouraging them to be materialistic?

McKellar: You think my book is going to make them more materialistic than they are already being trained to be? You're putting my book on quite a pedestal. That's like throwing a drop of rain into an entire ocean. When they see these things reinforced in every part of society – and it does surround them – they'll start to make a connection to math they never would have before.

By the way, it's no accident that the cover of the book imitates a teen magazine. There is a horoscope. There are personality quizzes. This is what girls have gravitated towards. Who knows what the reasons are? Is it because of products out there? Equally important (is that) girls from that age start to ask the important question, "Who am I?" They will ask it for the rest of their lives.