The hex key is 5/64 of an inch, which is small enough to lose in a pocket seam and exactly the size of the set screws on our robot's arm. I've carried it since October. It's in my jacket right now.

I was the one who decided to put the big arm on. That's the sentence I've been avoiding for six months, so I'll say it first.

Two nights before regionals, our robot had a polycarbonate arm that could score in the low goal all day. It was boring and it worked. On a cart in the corner of the shop sat the aluminum arm Marcus and I had been building since January: eleven inches longer, tall enough for the high goal, worth three times the points. We had run it maybe four times.

"We haven't tested it for more than ten minutes straight," Marcus said. He was holding the hex key out to me like it was a question.

"So we test it for twenty tonight," I said, and took it.

Priya, our driver, said nothing, which I decided meant she agreed. Ms. Okafor asked if I was sure, and I said yes with the kind of confidence you only have at 11:40 p.m. holding a Red Bull. We swapped the arm. I tightened every set screw myself and put the key in my pocket at 1:15. The arm ran twenty-two minutes without a hiccup. I remember thinking: see.

Qualification match three. Priya drove us to the high goal, the arm went up, and I heard it before I saw it, a click like a knuckle. The set screw on the shoulder shaft had stripped. The arm dropped. It fell across the intake and pinned it flat against the carpet, and for the remaining ninety-one seconds our robot sat in the middle of the field like a dropped umbrella while three other teams drove around us. Priya's hands stayed on the controller until the buzzer.

In the pit afterward, nobody said anything. Marcus pulled the arm off and set it back on the cart. I put the hex key on the table, and Marcus said, "Don't," and pushed it back at me. "You're not doing the thing where you resign."

"I wasn't."

"You were."

We finished twenty-seventh out of thirty-four.

The month after regionals was hard, but we got through it. We had a lot of long conversations as a team about what had gone wrong and how to make decisions better. I apologized to everyone. We rebuilt the arm, made a testing checklist, held more structured meetings, and by the time the state qualifier came around we were a much stronger and more communicative team. I also became a better listener and a more humble leader.

The night before the state qualifier, Marcus wanted to swap a motor controller that had been running warm. He had the hex key, and he held it out to me the same way. I didn't take it. "What does Priya think," I said, and Priya said, "Leave it," and we left it. We placed ninth. Nobody will tell that story at the banquet. But the arm stayed up.

I learned that being captain doesn't mean having the boldest idea in the room; it means making sure the room gets to weigh in before the idea becomes a robot. I learned that "we'll test it tonight" is not a test plan. And I learned that the people who go quiet when you ask if they're sure are usually not agreeing with you. I still carry the hex key. It reminds me that the smallest part is the one that can drop everything.