“We are,” I said. My foot slid higher, brushing the inside of his thigh now. “I’m learning all kinds of things.”
His breath caught. He gripped the edge of the table. “You’re impossible,” he whispered.
“You like it.”
He bit his lip and tried to glare at me. Tried and failed.
“Fine,” he said, and there was challenge in his voice, steel underneath the pink cheeks. “If it helps you focus, be my guest.”
My pulse kicked.
I liked this. I liked it when he got stubborn. When he refused to back down, even though I could see the way his breathing had changed.
“Deal,” I said.
He cleared his throat and looked back down at the notebook. “As I was saying. Standard deviationmeasures the spread of data points around the mean. The formula involves…” His voice wavered as my foot slid higher, tracing the length of his thigh. “It involves squaring the differences between each value and the mean.”
I kept my expression neutral. Interested student. Totally focused.
My foot moved with purpose now, feeling the tension in his leg as his muscles went taut.
“Keep going,” I said. “I’m following.”
He swallowed. “Then you sum those squared differences and divide by the number of observations.”
My foot reached the top of his thigh. I felt the heat there. Felt the way he shifted in his seat, trying to maintain composure.
“And then you take the square root,” he continued, voice strained. “Which gives you the…the…”
I pressed gently. Not too much. Just enough.
His words died. His cock throbbed hard under the layers of clothes and the pressure of my foot.
“Standard deviation,” I finished for him. “You take the square root to get the standard deviation.”
His eyes snapped to mine, wide and startled.
“I’m listening,” I said softly. “Promise.”
He exhaled shakily. “You’re…this is…”
“Unconventional,” I supplied. “But very educational.”
He opened his mouth. Closed it. Tried again. “You’re going to get us kicked out.”
“No one’s looking at us.” I kept my foot exactlywhere it was. “They’re all focused on their own work. Just like we are.”
“We are not…” He cut himself off as I moved again, just slightly. His hand tightened on the notebook until the pages crumpled. “Jason.”
“Tell me about variance,” I said. “That’s related to standard deviation, right?”
His jaw worked. “You know it is.”
“But I want to hear you explain it.”
His chest rose and fell. He was fighting to keep his breathing even. I loved watching him lose that fight.
“Variance is the square of standard deviation,” he said, each word careful. “It measures…” I shifted my foot, and he gasped, quiet but unmistakable. “It measures the average squared deviation from the mean.”