As the 2025-2026 school year commences in full swing, the PDS community has welcomed many new faces, both students and faculty. One such person is Mr. Justin Sheehan who comes to the school as the new Computer Science and Innovation Department Chair.

Mr. Sheehan first began teaching at the Catherine Cook School in Chicago, where he taught graphic arts and computer science at the middle school before earning his master’s degree in STEM education; other than that, however, Mr. Sheehan has spent the vast majority of his time teaching internationally, with much of the past decade focused on schools in countries like China and Tunisia,with the latter being where he most recently taught before coming to PDS. While in Tunisia, he met current Math Department Chair Ms. MacDonald whom he cites as the reason for connecting with PDS: “[She] messaged me and said, ‘I feel like they’re designing your job,’ and that was really exciting and cool,” Mr. Sheehan recalled.

Mr. Sheehan’s passion in his field of computer science began early in his childhood: he spent many summers“building model rockets or model airplanes, constructing different devices,” he described, “I just always loved tinkering and I think as tinkering became more digital I got more and more into computer science.” This interest in engineering and electronics continued throughout his time in college where he obtained a bachelor’s degree in commerce, where he discovered a love for the statistical and data analysis side of his field which combined with his preexisting love for tinkering fully brought him to where he is today in his field, describing it as, “[They] just sort of came together to form a calling.”

When asked about particular influences both in his career and life,  Mr. Sheehan named authors from his childhood: Brian Jacques, whose Redwall series taught him empathy and moral duty, and Terry Pratchett, who taught him to question things and wonder about systems in life. “Those [two] kind of set me up for teaching and for influencing students,” he explained. For his influences in computer science, he names Carl Sagan and Cory Doctorow, an ethics of computer science writer, as two prominent figures. “I always look to literature, into podcasts, and to thinkers who are leading us in these disciplines that I study and I try to take from them what I can,” Mr. Sheehan added.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

As for advice for those who are new to the field of computer science, Mr. Sheehan recommends students not to create their own hurdles or limit themselves. He emphasizes  taking advantage of the large community within computer science, as more people collaborating means being able to compute faster and move forward. “It’s like AI today. The more computers you have, the faster you can build your AI model,” said Mr. Sheehan, “The more people you have exploring and trying and learning, the more powerful the growth of your discipline is going to be.” For students who are interested in computer science but are not currently in his classes, Mr. Sheehan suggests following their curiosity wherever it leads them and pursuing what excites them. “Don’t get stuck in courses and tutorials, just try things,” he advises.