By Catherine Brewster

For anyone who sees “screen time” as a menace to intellectual growth and a satisfying life, the case of the young Chris Spalding is perplexing. His path to teaching physics at Commonwealth began with the nature documentaries, especially about space and dinosaurs, that he loved as a child: “the deeper you look, the more fascinating it gets.” Growing up just outside Belfast, Northern Ireland, he wasn’t above video games, either; their soundtracks introduced him to heavy metal, paving the way to wild acclaim for his talent-show work on guitar, drums, and bass at Hancock. But he indisputably got his homework done, too, counting among his bandmates his Ph.D. advisor at the California Institute of Technology. His years at CalTech followed an undergraduate degree in astrophysics at the University of Cambridge.

A self-described “polite, quiet, introverted rocker,” Chris chose the Cambridge college, Fitzwilliam, that was the most remote from the pubs. He envisioned a research career in astrophysics, and indeed went on to publish papers in collaboration with people like his wife, Sarah Millholland, who now studies exoplanets at MIT (and gave an assembly talk at Commonwealth two years ago, introducing a spellbound audience to categories like “hot Jupiters”). One of Chris and Sarah’s joint publications explores the circumstances under which, in some planetary systems, “the inner planets impulsively acquire misalignments that scale with the stellar obliquity.” Chris’ own doctoral research focused on the rotations of stars. Our sun rotates in the same direction in which the planets orbit, which makes sense since the whole system presumably collapsed from the same cloud—stars in some other planetary systems, though, rotate “backwards,” or in ways Chris sometimes called “upside down and inside out” in talks. He used computer simulations to examine what might explain the differences.

Across his years of doctoral and postdoctoral research, at Yale, Princeton, and MIT, “I tried my hardest to stay broad,” Chris says. He gently rejects Ernest Rutherford’s haughty proclamation that “all science is either physics or stamp collecting.” He would have loved to study biology, he says, if only he’d “figured out sooner how to write essays about it”; at CalTech, he collaborated with an “archetypal geologist with a giant beard” to build a model of a mass extinction event caused by ocean acidification, looking at the physics of how animals form shells.

He also began to notice that while many of his peers seemed happiest when they could “sit in the basement and code,” he loved giving talks at conferences: “I realized that I’d sat in my basement and coded just so I could give the talk—that was the fun part.” (He also recalls a “talk about giving talks” whose message resonated: “Your slides are the backup singers; you are the rock star.”) At the same time, he found himself discouraged by the forces pushing him toward narrower and narrower focus: “once you’re six papers deep into a topic and there’s a competing team with another model and there’s not really the data to test them.”

At Princeton, he began to think seriously about high-school teaching. The answer to “How can I see what that’s like?” was to teach math to incarcerated people, a choice whose causes and effects he explains very carefully. “I went in there for me, but I stayed because I really liked it. I had never thought about these kinds of issues, about people society has forgotten.” The most advanced material he taught was Algebra I—his students “had never had the chance to have that education. They didn’t have anything to lose. They were just trying to show the world that they mattered. And even though I was just teaching them how to factor polynomials, it forced me to say to myself: How can I think about this in a way I’ve never thought about it before?”

Even if the eleventh and twelfth graders learning physics from Chris at Commonwealth couldn’t be farther, in their preparation and opportunities, from the incarcerated people he taught in New Jersey, two principles have nevertheless stuck with him. The first is that “the only time you truly understand something is when you have to teach it.” He started his new astronomy elective this year with a unit on historical figures, confronting some regrets about his own high-school performance in history—“the only D I got”—and realizing for the first time that figures like Aristotle, Ptolemy, and Aristarchus lived hundreds of years apart.

The second principle underlies the conception and design of the astronomy course: he looks for ways to resist patterns whereby, as he puts it, “the rich get richer.” For instance, Commonwealth students who can tackle calculus-based Physics 1 Advanced as juniors can go on to Physics 2. In his algebra-based physics courses, on the other hand, Chris noticed “students who love science as much as I did but have not gotten the math to be able to jump into astrophysics, who I thought weren’t really being seen by the STEM curriculum.” He built the astronomy elective partly for them, with Algebra 2/ Precalculus and Chemistry 1 the only prerequisites. For him, that meant using last summer’s Hughes/Wharton grant (funds for faculty enrichment, named after two of their champions at Commonwealth: John Hughes and Bill Wharton) to figure out how he could set assignments that tested students’ understanding without the kind of math he would include in physics problems. “Flexing that muscle,” he recalls, was a lot of fun.

Astronomy, Chris makes clear, won’t be the only elective he develops at Commonwealth. Earth science and a second-year course in classical mechanics are among his ideas, along with “a dinosaur course. I really, really love evolutionary biology.” For this year’s Earth Day assembly, organized by the Environmental Club, he offered a workshop on the physics of carbon dioxide as a greenhouse gas. Since I include a few weeks’ worth of readings on climate science and policy in my twelfth-grade course, Reasons for Writing, I signed up. In ten minutes, Chris filled in a gap in my understanding of the history as well as the science: he cited the work not of John Tyndall or Svante Arrhenius, the big names I associated with “carbonic acid” and climate change, but of Eunice Newton Foote, who demonstrated the greenhouse effect experimentally in 1856, three years before Tyndall. “I like to show that women do things,” Chris acknowledges dryly. With luck, all kinds of students will do things in his classes for years to come.

Catherine Brewster has taught English at Commonwealth since 2000. This article originally appeared in the summer 2025 edition of CM, Commonwealth's alumni/ae magazine. 

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