Over English-muffin pizzas in the cafeteria, Kirsten began dishing out details of last weekend’s big party. Like Megan, Kirsten was only a sophomore, but she was a sophomore on the swim team, and that earned her a place on the periphery of the high school’s movers and shakers. Megan the math whiz had resigned herself to living in some parallel world that Kirsten would visit, bringing news from the planet of the popular.

In fact, it was Kirsten who’d relayed the rumor that Mr. Davis’s wife had left him after he found her in the arms of another woman. Megan had been skeptical at the time. “Is this from the same source who said Peter Green’s kid brother was abducted by aliens?” But the idea had stuck in her head.

“Earth to Megan.”

Megan blinked. Kirsten was waving a hand. “How many fingers am I holding up?” she asked.

“I’m sorry,” said Megan. “My mind went on vacation. Kirsten, did you notice anything different about Mr. Davis today?”

“Sure. That tie was a joke. He really needs someone to coordinate his clothes.”

“No, no. I mean, the way he acted.”

Kirsten contemplated the question for a few seconds. “Don’t think so,” she said. “Why?”

“No reason. I just thought he might have something on his mind.”

“Nothing ’cept Teddy R.” And with that, Kirsten was back to who kissed whom when the lights were out, a subject so complex that Megan had to skip dessert to make Mr. Thorndike’s trig class.

That night, Megan lay in bed and stared at the ceiling in frustration. Mr. Davis had read her letter, she was sure of it. And that was all she’d wanted. Right? Right.

But now she wanted something more. She felt scared and slightly sick, as if she’d sipped one drink and woken up an alcoholic.

What is enough?

She would lose everything if this got out, all the perfectly typed papers, all the extra-credit work, all the endless activities amassed like gold pieces for her college hoard.

What is enough?

Not this, not yet, she thought.

So she converted it into a math problem. “Given that Ms. Bryant wants an explicit, sexual response from Mr. Davis, and given that Ms. Bryant in no way intends to reciprocate, and given that Mr. Davis may under no circumstances learn her identity, show there exists a procedure to obtain this response in a manner that preserves both Ms. Bryant’s chastity and her anonymity.”

That was better. “Now use your brain,” she said softly to herself, calling her well-worn homework mantra into service. “Use your big brain.” Time passed. She waited. And the answer appeared, a red apple hanging from a black bough.