From Calculus to Curling: Q&A with SCH’s Math Department Chair

What do math equations or Olympic curling have in common? More than you think, according to SCH's Department Chair, Derrick Keister. We recently sat down with him to talk about his teaching, his hobby of curling, and the way they intertwine both in the classroom and on the ice.

SCH: Can you tell us a little about your role here and what you love most about SCH?

DK: I’ve been at SCH for about eight years, and since I began, I’ve served as the Mathematics Department Chair for grades 5–12. In addition to that role, I teach Upper School math classes.

What first drew me to SCH—and what I continue to love most—is our willingness to be innovative and try new things. We truly put students in the driver’s seat, whether that’s academically, socially, or in leadership roles. In math classes, especially, we ask students to problem-solve, generate ideas, and think deeply before we step in with answers. I also appreciate how SCH works to integrate subjects rather than treat them in isolation. The world is messy and interconnected, and I think we do a great job of showing students how disciplines complement and inform one another.

SCH: Would you be able to explain the basics of curling?

DK: Curling is played with either two players (mixed doubles) or four players per team. The objective is to slide stones down a sheet of ice toward a target called the “house” and get as many of your team’s stones as close to the center as possible before the other team does. Points are scored based on how many of your stones are closer to the center than your opponent’s closest stone. Players sweep the ice in front of a moving stone to control its speed and direction. The house is made up of concentric rings that visually mark distance from the center, each radius spaced two feet apart.

"It's a sport that's easy to begin but takes a lifetime to master - much like learning. There's strategy, endurance, focus, and teamwork involved. And like education, it's about continual growth, communication, and integrity," - Derrick Keister 

SCH: How did your journey with curling begin, and what first drew you to the sport? And what position do you play?

DK: My journey started with my girlfriend at the time—now my wife. We were drawn to curling while watching the Olympics. It looked unique, strategic, and fun. When we both found ourselves in the Philadelphia area, we Googled local curling clubs and discovered the Philadelphia Curling Club in Paoli and the Bucks County Curling Club in Warminster. Around that time, there was also a major national curling event in the region, and we attended a “Learn to Curl” session. Between joining clubs, watching high-level play, and getting on the ice ourselves, we were hooked.

On a four-person team, there are four positions: lead, second, vice (or third), and skip. The skip calls strategy and manages the game. I’ve played every position. The role I take depends on the experience level of my teammates. If I’m playing with more experienced curlers, I might play front end (lead or second). If I’m playing with less experienced teammates, I may play vice or skip. So yes—“play” is absolutely the right word!

SCH: Do you take part in competitions?

DK: Yes! In addition to local leagues, my wife and I have traveled to compete in Boston, New York, the Carolinas, and Long Island. Some competitions were for newer curlers, while others put us well out of our comfort zone against highly experienced players, which was a great way to learn. For a period of time, we focused heavily on mixed doubles (2v2). We once competed in a regional tournament in Boston and finished 17th in the region, which was a highlight for us. Being regionally ranked was a proud moment.

SCH: Curling looks easy to many, but there is a lot more skill needed than is realized. Do you employ your math knowledge while curling?

DK: Absolutely. Curling is extremely visual and analytical. As a skip or vice, you track how much a stone curls, how fast the ice is, and how the surface conditions change throughout the game. You visualize the stone’s path from release to the house.

There’s geometry in calculating angles when stones collide—stones often deflect at 90-degree angles. There’s calculus in thinking about rates of change as stones speed up or slow down. There’s physics in understanding force vectors and motion. Even the ice surface is fascinating: it’s “pebbled,” meaning small bumps are sprayed onto it. The bottom of the stone is concave, so only a thin ring contacts the ice. Counterintuitively, less pebble makes the stone slower. So yes—there’s a lot of math and science happening on the ice.

SCH: Do you ever bring examples from curling into your math classes? If so, how do students respond?

DK: In calculus classes, we’ve talked about rates of change using the speed of a curling stone. In classes involving parametric equations, we’ve discussed modeling the path of a stone as it curls across the ice. In geometry or physics contexts, we examine collision angles and force vectors. Students tend to enjoy seeing math applied in a real and somewhat unexpected context. It makes abstract ideas more tangible and helps them see that math truly exists beyond the classroom.

SCH: What lessons from curling—such as strategy, teamwork, or adaptability—carry over into your work as an educator?

DK: Curling is built on communication. When a stone is thrown, the thrower immediately communicates with the sweepers, who communicate with the skip. There’s constant collaboration in a matter of seconds. That mirrors the classroom environment, where communication between students and teachers—and among colleagues—is essential.

There’s also integrity. Curlers are expected to call their own fouls. If you accidentally touch a stone (“burn” it), you admit it. That expectation of honesty and humility has shaped me personally and professionally. Being willing to say, “I made a mistake,” or “I need to improve here,” is critical in both curling and education. Finally, as a skip, you must know your teammates’ strengths and areas for growth. You call a game that both supports and stretches them. That’s very similar to teaching—meeting students where they are while still pushing them to grow.

SCH: What’s one surprising connection between math and curling that people might not expect?

DK: One surprising connection is how deeply geometry and physics are embedded in stone collisions. When one stone strikes another, the motion often transfers along a perpendicular (90-degree) path. Understanding where to hit a stone to send it in a desired direction involves visualizing angles and force vectors—very much like solving a geometric proof in motion.

SCH: What advice would you give students who want to pursue interests outside the classroom while maintaining their academics?

DK: I strongly believe students need both. Academics alone don’t fully prepare you for life, and extracurricular experiences alone don’t either. It’s the balance that builds a well-rounded person. My advice is to pursue your interests wholeheartedly—but thoughtfully. Use your support systems. Learn to manage your time. Don’t let academics fall away in pursuit of an activity, and don’t let activities disappear in pursuit of academics. The growth happens in holding both together.

SCH: Are you looking forward to watching curling in the Olympics?

DK: Absolutely. My wife and I love watching both the Summer and Winter Olympics, but I’ve always been especially drawn to the Winter Games. We watch live events in the morning, catch prime-time recaps in the evening, and follow along with the Olympic apps.

We were especially excited to see Team USA earn a silver medal in mixed doubles—an event that’s meaningful to us since that’s what we play together. It’s also special this year because the lead player on the U.S. women’s team, Taylor, has local ties. I’ve taken training sessions with her father, who is highly respected in the curling community, and I’ve shared ice time with Taylor and her sisters at Bucks County Curling Club. Seeing someone you’ve practiced alongside compete on the Olympic stage is incredibly rewarding.

Curling is unique in that it’s played on a global stage, but the community itself is small and tightly connected. You can compete at the highest level in the world, yet still personally know many of the people involved.