(CNN)From Sierra Leone to Vietnam, the radio has long given a voice to children across the developing world. With the help of organizations like Plan International, radio programs educate children on a huge range of important subjects, from child marriage to emergency responses to natural disasters.
Radio gives voice to children worldwide
To mark World Radio Day, meet the young people taking over the airwaves.
"I've never met my dad. He went to live in Korea when my mother was pregnant with me. Ten years later, my mother followed -- leaving me behind to live on my own," says Quynh, 17, from Vietnam.
Even though Quynh's aunt looked after her, she couldn't help but feel desperately lonely.
Quynh was eventually able to move to a school nearer to her house and it was there she found hope. "I met my old friends and they suggested I apply to be part of a youth media club."
Two years later, Quynh became the host of her own radio show, Little Micro. Every Saturday morning she hosts a 30-minute program where she talks about the importance of child rights.
"Thanks to Little Micro, I'm no longer lonely. I have so many people who care about me, who share their stories with me, such as club members, friends and teachers. These people are also the massive audience who listen to my radio program every Saturday," she says.
Mariama, 14, from Sierra Leone is the seventh child in a family of eight siblings.
As the government of Sierra Leone fights to put an end to the Ebola outbreak that has plagued the country for nearly a year, all schools and universities have been closed in the country, bringing a halt to Mariama's lessons.
To keep up with her studies and to keep herself occupied, Mariama listens to the emergency radio teaching program called "School in a Radio."
Teachers deliver home lessons through 41 radio stations and children can learn without having to attend school.
"My family and I listen to radio on Ebola awareness and do what we are told to do to keep us safe," she explains. Mariama is hoping the Ebola outbreak will be contained so that she can go back to school in March when they are planned to re-open.
"I want the government to end the Ebola outbreak so that we can go back to school, that is my dream for 2015. Listening to the emergency radio teaching program and writing down my notes as I listen, is the only way I keep myself busy with school work. My mother is not working and she cannot afford the service of the private tutor."
Two girls listen to the radio as they hear updates of an incoming cyclone heading for their village. They scribble down notes and begin relaying information over their megaphone. Ears perk up as the message "cyclone coming" is read aloud. Within seconds, the room erupts into noise as students disperse into groups and their disaster simulation drill begins.
Welcome to Thandwe district, in Rakhine State, Myanmar, one of the least developed regions of the country. Located on the west coast, Rakhine has suffered devastating floods and tropical storms, such as Cyclone Giri, which killed an estimated 140,000 people in 2010.
Understanding that children are increasingly at risk, organizations such as Plan are trying to train children -- in schools and within their communities -- to understand the impact of climate change and to be prepared for natural disasters, via the medium of radio.
The young students rush in and out of the classroom as they rehearse the three main activities in a disaster response: early warning, search and rescue and first aid.
Bandages fly through the air, students playing as "medics" crawl around tables and chairs searching for community members hurt by the cyclone. Maps are drawn and evacuation routes are planned.
Things start to quieten down and students emerge from their evacuation shelters and return home. "It is safe to come outside now," the two young girls announce. "The cyclone has now passed." And with that, the disaster simulation is complete.
Chonatale, Nicaragua, is home to one of the highest rates of violence against women in the country. Yet a group of girls are determined to have their say on the issue, through their radio show, Girls in Action.
The teenagers, aged between 14 and 18, broadcast their radio show three times a week.
Each week, the girls discuss topics such as gender-based violence, sexual and reproductive health, as well as self-esteem -- which lets the community learn more about the issues they face.
According to Mariangel, 14, from Nicaragua, "some people do not have a television at home, but they do have radio. Furthermore, people who can´t see, listen to the radio, so through it they are able to know about things that are happening in their community -- such as violence, bullying, early pregnancy and trafficking."
Girls in Action has also let Mariangel tackle issues close to her heart such as bullying.
"In some radio programs we have recorded, I have spoken about bullying and it has given me the confidence to do something about it. At my school, I witnessed children who were being bullied. They were afraid. They felt threatened. So I went and spoke to them, and told them how they could seek help from a counselor."
Thanks to this project, Mariangel now feels inspired to study journalism and, one day, make radio her career.