It’s a life-and-death matter: Dealers are selling teenagers drugs made with fentanyl, and it’s killing thousands of them.

A groundbreaking campaign for the Real Deal on Fentanyl initiative from Joan and the Ad Council, “Substitute Dealers,” featured former drug dealers as substitute high school teachers, giving hard-hitting lessons related to the fentanyl problem.

Illegally manufactured fentanyl has become increasingly prevalent, appearing as a contaminant in illicit powdered drugs and being used to create counterfeit prescription pills, according to the Ad Council. Many young people are unaware of this shift, meaning that there is an increased risk of unexpectedly encountering fentanyl.

Creative agency Joan knew the answer to this threat wasn’t “don’t do drugs,” but rather to offer information from the people who knew. To do so, they replaced high school teachers with ex-drug dealers, who reimagined a normal school day through the lens of a fentanyl overdose. The former dealers came from diverse backgrounds, each with different experiences with drugs, fentanyl and recovery education.

The content was filmed at Holyoke High School in Holyoke, Massachusetts, an area affected by the opioid crisis.

To amplify the message, Joan shared the curriculum online, making it open-source, so that educators around the world could access it. The website received more than 1 million views, 340% over benchmarks.

“Young Americans are dying of fentanyl overdoses at a staggering rate, and the time to act is now,” said Lisa Sherman, president and CEO of the Ad Council. “We’re so grateful to all our partners who are joining us in the fight against the overdose crisis and delivering critical information during a time of need. This powerful coalition is uniquely qualified to reach and influence young people and will allow us to make an extraordinary difference and save lives.”