Kids, teens and their great big ideas

Over 85 percent of all pancreatic cancers are diagnosed late, when someone has less than two percent chance of survival. How could this be? Jack Andraka talks about how he developed a promising early detection test for pancreatic cancer that's super cheap, effective and non-invasive -- all before his 16th birthday.

Raymond Wang is only 17 years old, but he's already helping to build a healthier future. Using fluid dynamics, he created computational simulations of how air moves on airplanes, and what he found is disturbing -- when a person sneezes on a plane, the airflow actually helps to spread pathogens to other passengers. Wang shares an unforgettable animation of how a sneeze travels inside a plane cabin as well as his prize-winning solution: a small, fin-shaped device that increases fresh airflow in airplanes and redirects pathogen-laden air out of circulation.

Plastic bags are essentially indestructible, yet they're used and thrown away with reckless abandon. Most end up in the ocean, where they pollute the water and harm marine life; the rest are burned in garbage piles, where they release harmful dioxins into the atmosphere. Melati and Isabel Wijsen are on a mission to stop plastic bags from suffocating their beautiful island home of Bali. Their efforts -- including petitions, beach cleanups, even a hunger strike -- paid off when they convinced their governor to commit to a plastic bag-free Bali by 2018. "Don't ever let anyone tell you that you're too young or you won't understand," Isabel says to other aspiring activists. "We're not telling you it's going to be easy. We're telling you it's going to be worth it."

Taylor Wilson believes nuclear fusion is a solution to our future energy needs, and that kids can change the world. And he knows something about both of those: When he was 14, he built a working fusion reactor in his parents' garage. Now 17, he takes the TED stage at short notice to tell (the short version of) his story.