A triathlon can seem daunting to the average adult, but on Saturday 650 kids in Connecticut will take one on—swimming, biking and running in memory of a 7-year-old boy killed in the Sandy Hook Elementary School shooting in 2012.

Chase Kowalski was extremely athletic. He competed in his first triathlon the summer before died.

“One night he came in after swimming with my husband in the pool and was like, ‘Mama, I want to do that thing,’ Rebecca Kowalski recalled. “And I said, ‘What thing?’ And he said, ‘Where you swim and you bike and you run.’ And I laughed. I said, ‘Chase that’s a triathlon and that’s not for kids.’ And he gave me my iPad and he said, ‘Here. Google it.’ I googled it, and I found one for kids. Two weeks later he was doing a triathlon.”

Chase came in first in his age division. A photo from that race shows him smiling big, showing off the medal around his neck.

“He was great at everything he did. He put 110% effort into every sports activity,” remembered big sister Erin Kowalski.

The Kowalskis started the CMAK Foundation and Race4Chase triathlon training program in 2014 to honor Chase’s spirit. Race4Chase started with three camps and about 90 kids that first summer. Now there are 29 camps. Most of them are in Connecticut, but the program has also expanded to Rhode Island and South Carolina. Almost 1,000 kids are enrolled this summer.

“It’s amazing. I mean, I knew it was going to be big. I didn’t know how big, but Chase has always given us the inspiration to grow,” Rebecca Kowalski said. The program is for ages 6-12 and is free. For kids that don’t own a bike, one’s given to them. Race4Chase runs for six weeks and culminates with a triathlon for all the kids in each state.

Erin Kowalski has been a part of the program for several years. This summer she’s the head coach at the Newtown Community Center branch of Race4Chase.

“This means I can let my brother’s legacy live on and let other kids enjoy a sport he loved to do,” Erin Kowalski told News 12. She teared up remembering Chase, whom she called “the best big brother,” but said she sees him in every kid she coaches. “This has been my main source of therapy and getting to just heal anything that I can. I get to still feel like he’s around me even though he’s not.”

Rebecca Kowalski echoed her daughter. “The beauty is that we get to watch these kids grow up because most of the kids that go to the program that enjoy it, they come back year after year, so I’ve gotten to see them grow. And that’s been bittersweet but yet amazing.”