Principal David Lon of Jules E. Mastbaum High School in Kensington is a proud graduate of the Philadelphia public school system and an alum of Frankford High School. His journey to a career in education began at Temple University, where he initially enrolled as a journalism major, drawn to reading and writing. 

“I come from a family of trades,” Lon said. “My dad was a steelworker, my mom was a waitress, my brother’s a carpenter, my other brother’s a mechanic. My trade was I could read a book and write an essay about it.” 

But during his second year at Temple, Lon began to sense that the journalism industry was shifting and questioned whether it was the right long-term path. Teaching English felt like a natural fit for his interests and abilities, leading him to change his major to secondary English education in 2001.  

“That aligned with who I am as a person,” Lon said. 

What kept Lon in education, however, was not content alone. It was a purpose. As a Philadelphia native serving Philadelphia students, he became deeply committed to the social justice responsibilities of the profession. 

“Addressing students’ needs is an important part of our job,” Lon said. “You have to embrace that to be successful educating kids in this city.” 

Lon credits mentors with helping him recognize his leadership potential early in his career. He worked with his second principal, Hiromi Hernandez, at Furness High School who appointed him English department chair while he was still in his twenties.

“She saw something in me,” Lon said. “Even though I was the youngest person in the department, she trusted me with leadership.” 

Another pivotal influence was Tim McKenna, longtime principal of Central High School, who modeled a leadership style that balanced accountability with humanity. 

“When I watched him do the job, I realized you could be a leader in the field and still be a relatable, down-to-earth human being,” Lon said. “That’s when I could see myself in that role.” 

After 14 years teaching at Horace Furness High School, Lon became an assistant principal and spent two formative years at Simon Gratz Mastery Charter 

In 2019, Lon became principal of Jules E. Mastbaum High School during a period of instability. The school faced significant climate challenges while serving a community deeply affected by the opioid epidemic. Lon focused on rebuilding trust, developing staff, and creating systems that prioritized safety and belonging. 

His leadership philosophy centers on talent recruitment, development and retention. 

“I develop people so that people can develop their children,” Lon said. “I’m only as successful as the people I work with allow me to be.” 

For Lon, leadership remains rooted in service, mentorship and trust. 

“You always make decisions for kids,” he said. “You treat people like people, and you trust the work they’re doing. That’s how schools grow.” 

That approach has produced measurable results. Lon shared, “Mastbaum became one of only three schools in the district to show growth across every district performance goal and the only high school to do so.” He was recognized at a district meeting by Superintendent Tony B. Watlington, and then Deputy Chief of Schools and now Deputy Superintendent of the School District of Philadelphia, Jermaine Dawson, who asked him to share Mastbaum’s success at the meeting.  

“That data didn’t move because of me,” Lon said. “It moved because of teachers, leaders and staff who have been doing the work together for years.” 

Lon’s relationship with Temple has come full circle through his partnership with the Temple Teacher Residency, working closely with Amy Scallon, associate director of clinical practice, to support future educators. Mastbaum has hired extensively from the program, and Lon regularly returns to campus to lead workshops and mentor aspiring teachers. 

“Temple prepared me to be a practitioner in the city,” Lon said. “Coming back to Temple now as a principal feels incredibly meaningful.”