High school senior Mimi Yen spends a lot of time thinking about worm sex.

At Yen's lab at New York University, where she studies worms under a microscope after school, she can point out which ones are hermaphrodites.

Yen's career plans are set: She is pursuing a career in the sciences -- a field still dominated by men.

Overall, women make up nearly half the U.S. workforce. But they hold less than a quarter of the jobs in science, technology, engineering and math.

And those jobs pay well, too: The average annual income of a college-educated worker in the sciences is $74,000, compared to $59,000 for college grads in other fields, according to federal data.

"In the classroom setting, a lot of the people who raise their hands are boys," said Yen.

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