First lady Michelle Obama says she is "outraged" and "heartbroken" over the kidnapping of hundreds of Nigerian school girls who risked their lives to get an education, saying she hopes their story serves as an inspiration for American students to work harder and appreciate what they've got.

"In these girls, Barack and I see our own daughters. We see their hopes, their dreams - and we can only imagine the anguish their parents are feeling right now," Mrs. Obama says in her first-ever weekly address. "Many of them may have been hesitant to send their daughters off to school, fearing that harm might come their way. But they took that risk because they believed in their daughters' promise and wanted to give them every opportunity to succeed."

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It's been more than three weeks since the girls were taken from their school by extremist militants from Boko Haram, "a terrorist group determined to keep these girls from getting an education - grown men attempting to snuff out the aspirations of young girls," she says.

The first lady said that her husband's administration is doing "everything possible" to support the Nigerian government's search for the girls.

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Noting that more than 65 million girls worldwide are not in school, she says "what happened in Nigeria was not an isolated incident… It's a story we see every day as girls around the world risk their lives to pursue their ambitions."

"Education is truly a girl's best chance for a bright future, not just for herself, but for her family and her nation," she added. "And that's true right here in the U.S. as well… so I hope the story of these Nigerian girls will serve as an inspiration for every girl - and boy - in this country. I hope that any young people in America who take school for granted - any young people who are slacking off or thinking of dropping out - I hope they will learn the story of these girls and recommit themselves to their education."

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"These girls embody the best hope for the future of our world… and we are committed to standing up for them not just in times of tragedy or crisis, but for the long haul," she says. "Let us show just a fraction of their courage in fighting to give every girl on this planet the education that is her birthright."