A quick search on social media and you'll find all sorts of videos of people vaping. One device that's popular right now, the "JUUL," which looks like a USB.
There's even a popular hashtag and Instagram page, #doit4juul.
"It's an easy way to hide something that they should not be doing, period," said Jennifer Liewer with the Tempe Union High School District.
She says vaping isn't allowed at any of the district's seven high schools. But now with vaping devices looking more like everyday items, teachers are on the lookout.
"We had one student who was charging theirs in their classroom and for a very short period of time people didn't realize what they were doing," Liewer said.
One student even tried to hide in a school closet to vape. They were caught after setting off the school's fire alarm.
Vaping seems to be on the rise across the country. A survey done in 2017 by the National Institute on Drug Abuse found that one in six 8th, 10th and 12th graders used a vaping device in the last 30-days.
Doctor Frank LaVecchio is a toxicologist with Banner Health. He says just a small amount of liquid nicotine equals a pack of cigarettes. "The one thing that we don't know is how this is going to affect people long-term," LaVecchio said.
The doctor says it could be 10 to 20 years before we know how vaping affects a young persons' developing brain.
As for JUUL, the company says no one under the age of 18 should have one of its devices, and the company is committed to combating underage use.