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"Exactly. But you’re not just looking at how fast you’re going. You’re watching how your speed is changing in relation to the puck. That’s a derivative. It’s rate of change."

Axel’s face lit up. "Ohhh. Like acceleration."

"Exactly."

I pivoted to Rory, scrambling for an analogy that would work for him.

We were looking for performance over time which kind of translated perfectly with hockey.

I just had to choose a metric. "Okay, for function notation. Let’s say your shot percentage is a function of ice time.

” I turned to the board and scribbled: f(x) = shot % based on x minutes on the ice.

“So f(x) is how well you shoot depending on how long you’re on the ice.

If we plug in thirty minutes of game time—f(30)—what do we get? ”

"A broken stick and ten minutes in the penalty box?" Axel leaned back in his chair like he was waiting for applause.

Rory elbowed him with a crooked grin. “Try a goal or two.”

I laughed. “Perfect. Because what we’re looking for isn’t only the number of shots. We’re looking for the output of a relationship—something measurable that changes as your input does.”

Rory’s brow furrowed, but the wheels in my head were spinning at full speed.

“No, this is amazing. Think of it like this. If we want to know how effective you are in a game, we’re not just looking at your total shots.

We’re looking at what you do per minute of ice time.

We want to know, ‘If I put Rory on the ice for ten more minutes, what’s the expected outcome?

’ That’s your function. f(x) tells him what to expect at x minutes. ”

Rory blinked. “So like . . . f(10) might be one goal, but f(30) might be four?”

“Pfft. Try two.” Axel teased.

“Yes!” I grinned. “Exactly that.” I gave a nod to Axel. “And if your percentage starts to drop the longer you're out there, the function can show that, too. Coaches use this kind of thinking all the time. It’s how they decide when to rotate lines.”

He squinted at the equation again, then nodded, slowly. “So it’s kind of like my whole performance, graphed.”

I stared at what I’d written on the board. Holy shit. That’s exactly what this was. “Yeah. It tells you what output you get at a certain input. Like a vending machine. You press A6, you get a Coffee Crisp. You press A7, you get a sad granola bar.”

Axel exhaled. “Tragic.”

Rory turned the example over in his head, then reached for his pencil and started copying down the formula. “That makes way more sense. When I read it in the book, it made no sense.”

I couldn’t help smiling. “Math is code for patterns. You already know the patterns. You’re just not used to seeing them written down.”

Rory looked up. “Do coaches use this?”

I turned my head to find Chase watching me. “I don’t know. Do they?”

Rory and Axel turned, waiting for an answer.

Chase cocked his head to the side. “It’s a little more intuitive.”

Intuitive? There was nothing intuitive about this. Our brains paid attention to sensory data inconsistently and magnified the importance of some things more than others. The only way to know how these guys performed on the ice was by looking at the numbers.

“You know our functions?” Axel waggled an eyebrow.

There was that eye drop. The gentle exhale. The ache was back in my middle. “Nope. I’m only the compliance coach.”

Only. Another piece of the puzzle. Was Chase happy with this job? Or did he want more?

“So what next?” Rory asked.

I set the chalk back in its silver bed. “Now you do problem sets.” Rory balked. “Don’t worry, I’ll help you.”

Axel raised his hand. “And then cookies?”

Chase grunted. “You've already inhaled half the bowl.”

Rory grinned. “Yeah, but now we’re earning them.”

The rest of the session sped past. I helped both of them with their problem sets, thrilled that they actually understood. By the end, they were getting most of their answers right without any input from me.

“When we talk to your professors tomorrow, you’re going to show them this.” I slipped my notebook into my bag.

Rory looked hesitant. “What if I don’t remember any of this tomorrow?”

“No problem. We’ll go through more questions. Math is about repetition. Patterns of thinking change with practice. And the good news is, with your other classes, it’s mostly memorization. I have tricks for that, too.”

Axel jumped up and took a cookie from the bowl. “Can I take these to practice?”

I started to shake my head, then thought better of it. “Actually, yes. But tell the boys they won’t get anything else unless they show up to studying sessions.”

Chase stood and sauntered to the bowl. I gave him a look as he reached in and took two cookies. “What? I showed up to the studying session.”

I fought a grin as my chest warmed. The fact that he loved my cookies shouldn’t have made me feel more proud than I did when I got that quiz back from Kowalski. But it did.

Axel and Rory packed up, and Axel grabbed the bowl. “I promise you’ll get this back.”

“I better.”

Rory swooped back and gave me a hug. “Maddie girl. You’re the best.”

I blushed at the flattery as they left, then scooped up my own bag and slid the straps over my shoulders.

Chase sighed. “Go ahead. Say it.”

I glanced up. “Say what?”

“That I was wrong.”

I couldn’t tamp down the smile that time. “You were only partially wrong. The other guys didn’t show up. You called that.”

“I didn’t know you were such good friends with them.”

“With Axel and Rory?”

He nodded, brushing cookie crumbs from his lip.

“They’re good guys. And I think they care more than you give them credit for.” I adjusted my bag on my back. “Maybe they just need one person to believe they can be more than what they are.”

Chase’s jaw worked. I gave him a nod, then turned to the door. When I was almost over the threshold, he said, “Will you walk me through those functions? For the team?”

I turned back. “I thought it was intuitive.”

Chase shrugged. “I thought you were a teacher’s pet.”

“Teachers. Not coaches. There’s a difference.”

His lips twitched. “Smart ass.” I mimed a curtsy, and he laughed. “I haven’t seen anyone run numbers like that. It could be helpful. Especially with Canada West coming up.”

The Canada West University Hockey Championship. Last year, the Outlaws had just missed qualifying for the CIAU University Cup—the national championship held each spring. “I could do that.”

Chase drew in a breath. “Are you—do you have plans now?”

I wet my lips, my brain short-circuiting. Did I have plans? I couldn’t think past Chase standing with his hands in his pockets in front of me. “No. I don’t have plans. But?—”

“But what?”

My stomach grumbled. “I will need to eat at some point.” Unlike him, I hadn’t downed four cookies in the last hour.

Chase’s mouth quirked. “I can take care of that.”