Rachel Rosenfeld, 17, founded the R.S. Rosenfeld school in Srah Khvav village in Siem Reap province, Cambodia.

During Rachel Rosenfeld’s junior year in high school, the unexpected happened. She developed a stomach condition that kept her out of school the whole year. While recovering, her sense of purpose changed after reading a New York Times article on the plight of young Cambodians.

The article followed a 17-year-old girl who most likely would have been forced into prostitution if she didn’t go to school. The problem was that there were no schools in the girl’s village. Rachel, now 17 herself, remembers how the story inspired her to write letters asking for donations so the girl could go to school.

After hundreds of letters were forwarded organically across the country, Rachel received $52,000 in donations. In December 2007, she attended the opening of the R.S. Rosenfeld School in Cambodia’s Siem Reap province. Now, 300 students there can get an education thanks to funding from an unexpected place.

Update: Watch the CNN.com Live interview

Tara Suri, 16, hopes to help to young children around the world achieve their full potential.

Bake sales and recycling are common fundraising tactics in middle school. But Tara Suri wasn’t baking cupcakes for just any common cause. Her cause was hope, literally.

When Tara was 13, she was more than saddened by her trip to India with her family. From her sadness sprung the idea of trying to help the orphans in India and Sudan whom she saw abandoned by their parents, sometimes found in garbage dumps. Tara started H.O.P.E., or Helping Orphans Pursue Education. It aims to give kids the opportunity to achieve their full potential with the basics, like a sturdy roof over their heads, that Tara and her friends sometimes took for granted back in Scarsdale, New York.

Now, at 16, she has expanded her cause with an umbrella organization called Aandolan, which means “a movement for change” in Hindi. Through that fundraising group, Tara now runs Turn Your World Around and Connect a Kid along with H.O.P.E., and a lot of it for kids growing up continents away who are in sad situations.

Update: Watch the CNN.com Live interview

Teen AIDS Ambassadors pose for a photograph in Tanzania.

Santa Monica, California, is far from Tanzania. But a group of high schoolers there makes the distance seem closer. The Crossroads Teen AIDS Ambassadors are the youngest certified educator-activists in the country working toward the eradication of the disease.

The California students bring their mountainous mission to Africa. They travel to Tanzania and other countries to help tell their young counterparts about the history of the pandemic, the virology of HIV, and the importance of safe sex. Kids from Tanzania have come to California to go through the program to experience and see inspiration of a life minus the disease.

The hours are long, the information is daunting, and the trek is substantial. But from the AIDS Ambassadors’ perspectives, even their small hands can help start move the mountain.

Update: Watch the CNN.com Live interview