Page 20 of The Save

"Are these the cookies?” Rory peeled back the tinfoil and grabbed two. Chase’s jaw ticked.

I breathed a sigh of relief. It wasn’t even close to three forty-five. "You guys came."

Axel strode toward me, his arms outstretched. “Wouldn’t miss it, Maddie girl.” I stood, and he gave me a huge bear hug.

Chase pushed his chair back and stretched out his legs. He looked like he was about to take a nap. “I thought you boys already had plans to meet with your professors this week.”

“Can’t get too early a jump on it, eh?” Rory dropped into the chair next to me.

I gave Chase a smug look. “No, you can’t.” I sat as both of them pulled out their books. Applied math for Rory and Calc for Axel, if I was remembering correctly. He was an engineering major. I couldn’t remember if Rory had declared or not.

“Proportional reasoning and function notation.” Rory said the words like he was announcing someone had died.

Axel opened his text. “Derivatives. You’re welcome.”

I grinned. Now this was a language I understood. I started with Rory, walking him through slope and rate of change, only to be met with blinking confusion.

Axel didn’t do much better.

"So you take the function," I explained, pointing at the equation, "and then you derive it. You take the exponent, multiply it by the coefficient?—”

I stopped when I noticed his blank stare. “You know what. Let’s try something different.” I stood and walked to the chalkboard. Thankfully, there was one half piece of chalk lying in the metal gutter.

I lifted it and drew a line. "Okay. Picture this. You’re skating full speed toward the net, but the puck’s getting away from you. What’s changing?"

Axel stared at the board. I waited until he finally said. "Speed?"

"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 doper minuteof 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.”

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