You don’t have to be an adult to make a difference. These inspiring teens changed the world before trading their Right Packs for laptop bags. Read on to learn how some of history’s most influential teens transformed their communities, their countries, and the world.

MARLEY DIAS

At age 11, Marley Dias noticed that most of the books she read in school were about white boys and dogs—not about Black girls like her. So she decided to launch an ambitious book drive and resource guide, #1000BlackGirlBooks, with the goal of finding and donating one thousand books with Black, female protagonists to schools so that other Black girls would be able to see themselves in the books they checked out of the library. The drive soon became a movement, bringing new attention to the lack of diversity in children’s literature and inspiring more than 9,000 book donations. Dias has also written her own book (“Marley Dias Gets It Done — And So Can You”) as part of her efforts to create more stories featuring Black girls. In honor of her achievements, Forbes made her the youngest member of the Forbes 30 Under 30 list and TIME included her in their list of the 25 most influential teens in 2018.

Louis Braille

When Louis Braille was born in 1809 in France, he could see—but by the age of five an infection left him completely blind. Braille attended the world’s first school for the blind, the Royal Institution for Blind Youth in Paris. There, he learned about night writing, a system of raised dots that let soldiers read messages after dark without giving away their location by lighting a torch. But it was extremely complicated and never really caught on in the military or among the blind. By the time he was 15, Braille had developed his own tactile system of writing, one which was much simpler and more practical. Today, Braille’s system remains largely unchanged, and is used by people all over the world.

Ryan White

As a 13-year-old growing up in Kokomo, Indiana, in the 1980s, Ryan White was diagnosed with AIDS following a blood transfusion. Although he was only given six months to live, White remained alive for another five years, during which he faced enormous stigma within his community. At the time, the public understood relatively little about AIDS. White would help change all that, coming to national attention when he fought for his right to continue attending school. A few months after his death in 1990, the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act was passed into law, providing critical federal funding for people living with HIV/AIDS.

MALALA YOUSAFZAI

The youngest Nobel Prize laureate is a young woman named Malala Yousafzai, an activist for female education from the Swat Valley region of Pakistan. When the Taliban occupied the area, they prohibited girls from attending school. Yousafzai spoke out against the ban. Her defiance angered the Taliban, who attempted to assassinate the 15-year-old when Yousafzai was riding a school bus after taking an exam. Incredibly, Yousafzai survived the attack and went on to found the Malala Fund, a non-profit organization that works to help girls everywhere safely receive a free, high-quality education.

MELATI AND ISABEL WIJSEN

A staggering 10 percent of all marine plastic pollution comes from the island nation of Indonesia. Sisters Melati and Isabel Wijsen set out to change all that when they were only 10 and 12 years old. They started a campaign to get plastic bags banned from Bali, the country’s main tourist hub. The sisters founded an NGO called Bye Bye Plastic Bags and went on to speak out at the United Nations in New York about the dangers of plastic bags. They successfully petitioned the government to ban the bags—as well as other single-use plastics such as straws and styrofoam—in 2019. Today, they’ve expanded their focus to the entire world. Bye Bye Plastic Bags has teams in more than 50 locations across the globe and has spoken at 450 events and to 100,000 students.

AVI SCHIFFMAN

In December 2019, 17-year-old Avi Schiffman created a website to track the spread of COVID-19 (commonly known as the coronavirus). At the time, COVID-19 had not been reported outside of China; today, Schiffman’s site has received tens of millions of hits from people around the world. One thing that makes the site stand out? Schiffman tracks the number of people who have recovered from COVID-19 as well as the number of serious cases and fatalities. Schiffman taught himself to code by watching YouTube videos at the age of seven. In the wake of George Floyd’s death, Schiffman also launched 2020protests.com to help people find local Black Lives Matter protests.

GRETA THUNBERG

TIME’s 2019 person of the year—also the magazine’s youngest person of the year ever—is a Swedish girl named Greta Thunberg. Now 18, Thunberg started a school strike for climate change three years ago, inspiring teens around the world to join her in the fight for the planet. She sparked a movement that spread all over the world, leading to multiple protests with more than a million students each in 2019. Thunberg has spoken at the UN twice, and in August 2019, she spent 15 days crossing the Atlantic in a carbon-neutral yacht to speak to U.S. lawmakers. Thunberg has inspired students all over the world to take action for the environment. That could mean joining a protest, spending more time in nature (with a Far Out 65), or choosing durable goods over reusable ones.