My first class of the day, every day of my senior year of high school, was in Mr. Zander’s room. It was on the second floor in the northwest corner of the building. I sat in the back row, close to the windows that looked across the street to Loomiller Park. On a spring day, like the one I am remembering now, the room would have been full of light. A bright, blue sky. Lots of green grass through the windows.

Almost every morning, Mr. Zander would start class by giving us a practice problem. He usually had it written on a white slip of paper. We would work on it, and then someone would write a solution on the chalkboard. On this particular Wednesday, I remember sitting there before the bell, and I can picture Mr. Zander standing beside his desk, also in the back of the room, with the folded white paper in one hand, rubbing his forehead with the other. In a quiet voice, he asked if anyone knew a student named Chad Zabler.

I was surprised to hear the name. For some reason, still waking up, delayed processing, just habitual shyness, I didn’t raise my hand. When no one else did, Mr. Zander sighed and said he didn’t know him either. I spent the rest of that class, at least, in a daze. Yes, I knew Chad. Ever since Hygiene Elementary. His wide smile, his never-changing buzzed haircut, his puffy Vans shoes with salmon-colored waffle bottoms.

With Taylor Gold, our mutual best friend at school, we formed a trio. Laser tag birthday parties and sleepovers at Taylor’s house. We ate lunch together, every day, and stood outside talking and watching all the other kids at recess together, every day, through our years at Westview Middle School.

When we got to Longmont High something changed. Or rather, I did. I felt I needed to forge a new identity. We were just down the road from Loomiller Park , standing on the corner of Francis Street. When the light changed, I turned away from Taylor and Chad and walked back into school alone. We never had lunch together again. The best I can say is that I was fourteen years old and sometimes kids treat each other that way. I was no better.

That memory haunts me now, and it did then, on that Wednesday morning a few weeks before graduation, when Mr. Zander told us that Chad Zabler died the day before.

It didn’t make sense. As if the windows with the big blue sky and green grass outside were suddenly cracked all the way through but no one mentioned it. And then someone was up there at the board working out the problem. Whatever it was, a limit, a derivative, an integral, I’m sure I have forgotten how to solve it.

At graduation Chad’s parents accepted his diploma from Mr. Olson. It was days after what would have been his eighteenth birthday, and that was more than eighteen years ago now. I haven’t forgotten him.