WINTER GARDEN, Fla. — On the wall of a classroom that is home to the West Orange High School TikTok club, large loopy words are scrawled across a whiteboard: “Wanna be TikTok famous? Join TikTok club.”

It’s working. “There’s a lot of TikTok-famous kids at our school,” said Amanda DiCastro, who is 14 and a freshman. “Probably 20 people have gotten famous off random things.”

The school is on a quiet palm-tree-lined street in a town just outside Orlando. A hallway by the principal’s office is busy with blue plaques honoring the school’s A.P. Scholars. Its choir director, Jeffery Redding, won the 2019 Grammy Music Educator Award.

Amanda was referring to a different kind of stardom: on TikTok, a social media app where users post short funny videos, usually set to music, that is enjoying a surge in popularity among teenagers around the world and has been downloaded 1.4 billion times, according to SensorTower.