"He looked at the world from an international perspective," said teacher Ryan Coleman.
Ricketts graduated from Stanford in 2009, then took a job in San Francisco, where he was making more than $100,000 a year.
He recently quit his job to take an unpaid position with KIVA, a nonprofit organization. Ricketts leaves for Mexico on Saturday, where he will spend the next four months.
Ricketts told Eyewitness News he wanted to be able to think about things he'd accomplished in terms of changing people's lives, not in terms of financial success.
Coleman said financial security has never been a priority for his former student.
"He doesn't look at life in terms of financial success. For him success is how much of an impact can I make on other peoples lives," Coleman said.
In Mexico, Ricketts will promote social mobility and expand entrepreneurship for the people in his new community. He said he learned a different perspective through community service in high school.
He's excited and apprehensive, but too busy to dwell on concerns.
"We'll see how it goes that first week, that first month," he said. "It's going to be a huge learning experience."
Ricketts is funding half the trip himself, then trying to generate the other half through fundraising. If you want to help, "like" his page on Facebook, or visit www.indiegogo.com/projects/301649.