Before teaching, Zul coached youth triathletes through swimming, cycling, and running, three sports where a child’s only opponent is the time they posted last month. He brought that yardstick into the classroom: a child in his class is measured against the child they were in September, and they can watch the gap close. Water competence runs through what he teaches, which counts for a great deal in a city built around water. Fourteen years in, he is still a student himself.

