When he realized it would cost too much to buy presents for all the children in his local hospital, then-9-year-old Campbell Remess started making teddy bears for them by hand four years ago. His generosity grew into Project 365 by Campbell, and more than 1,200 bears later Remess is auctioning some of his creations to send ill children and their families on vacations. Click through the gallery to learn more about Campbell and the other four 2017 CNN Young Wonders, youth making a positive impact on their communities. CNN
One of nine siblings, Campbell taught himself to sew by trial and error, using patterns he found online. He delivers bears to children in the hospital and sends them to others around the world. His shelves are full of dozens of bears getting ready to go off to the hospital this Christmas. CNN
After visiting a local bookstore that promotes African-American children's literature, Sidney Keys III couldn't believe the wide selection of books reflecting him -- something he noticed was scarce in his school library. To share his love of reading with his peers, Sidney created Books n Bros, a reading club that focuses on African-American culture and literature.
Boys between the ages of 8-12, at a fourth- through sixth-grade reading level, gather once a month to bond and discuss their featured book. Since September, his book club has grown to more than 50 members. The group's "Adopt A Bro" initiative sponsors members who need financial assistance. They also welcome "Big Bros," older mentors who apply to join a meetup and help lead the book conversation. Meghan Dunn/CNN
Christina Li is on a mission to bridge the gender gap in STEM fields by empowering and encouraging girls' interests in computer science.
In 2015, during her junior year of high school, Christina created Hello World, an annual computer science camp for middle school girls. During the free, weeklong camp -- attended by roughly 30 girls -- Christina teaches web development, programming, app creation and robotics. Robert Humphreys/CNN
During Hello World, students interact with women from the industry through video conferences and speaker panels, and they tour places like Google Ann Arbor and the University of Michigan's Engineering campus. "Sometimes it's pretty intimidating to walk in a room and not see anybody that looks like you," Christina said. "It was very obvious that something was wrong, so I wanted to do something about it." Robert Humphreys/CNN
Haile Thomas' dad was diagnosed with Type 2 diabetes when Haile was about 8 years old. Her family's journey to help him be healthier through food and exercise worked -- reversing his diabetes. In the process, Haile learned about childhood obesity and wanted to help young people live healthier lives. CNN
At 12, Haile started The HAPPY Organization -- an acronym that stands for healthy active positive purposeful youth. She and her group provide cooking lessons and nutrition education through camps and classes as well as community outreach events centered around healthy eating -- with a focus on children ages 6-13 and those in underserved areas. CNN
Ryan Hickman is passionate about recycling. After he learned about the process, he began by collecting his neighbors' recyclables. Soon family members and friends were saving their bottles and cans for him, too. The 8-year-old's efforts have since become a thriving, community-wide business that has recycled more than 275,000 cans and bottles -- a total of 60,000 pounds, and counting. Every week, he sorts through recyclables from his "customers" all over Orange County. He and his parents take them by the truckload to the local redemption center. CNN
Why does Ryan love recycling? "Because it saves the planet and it keeps bottles and cans out of the ocean for animals to not get sick or die," he told Ellen DeGeneres. Ryan is a Youth Ambassador at the Pacific Marine Mammal Center in Laguna Beach, California. CNN
All five 'Young Wonders' were honored during the live, global telecast of CNN Heroes: An All-Star Tribute. Michael Loccisano/Getty Images for CNN