Swap Poker

"i won! that's soo cool!", said Melody. "hummm, let me think. there are too many things to choose from!"

All the players were cautious: nobody knew what to expect from Melody. The most worried were Josie, Philipp and Jeremy.

Josie and Philipp had assets that any 13 year old girl would want to try. Philipp, especially, had noticed how she couldn't keep her eyes off his chest. He was proud about this, up until now that is.
Jeremy was worried because of his position as the older brother. If she ever wanted revenge about anything he might have done in the past, she now was in a position to get it.

No one could have imagined what she said, however.
"humm, i would like to swap knowledge about mathematics with Jeremy. please."

"What?! why would you do that?!", cried Jeremy
"I have a test on Monday, and I don't want to spend, like, the weekend studying so I thought you could study for me, maybe? I wanted to go the mall and stuff with Emma and Alice you know? I thought maybe if we swap back on Sunday evening you will have your knowledge back for school, and I will be ready for the exam. And if we don't, I'll still have your knowledge so I'll do great anyway. Pretty clever right?", said Melody.
"I have to say that you are very clever indeed", said Josie.
"Thanks! Don't worry Jeremy, I'll help you if you happen to have trouble with 8th grade maths ;)"
"Thank you sis'. I guess..."

Anna stood up to fetch some paper and a pen.
"Melody, can you write the hardest math problem you can think of?"
"Sure", she said.

She then casually proceeded to write an integral to be calculated.
When she was done, she handed the paper to Anna. Melody could not refrain from smiling when she saw her rising an eyebrow and frowning at the paper.
Anna gave the paper and the pen to Jeremy. "Try to solve it now".
That's when Jeremy's heart sank. He was never gifted at maths, but he always put the work necessary to pass, spending evenings and weekends if he had to. And there he was, not able to even understand a problem his little sister wrote.

"Here, let me help you", she said. "It's easy, really!".
She kept talking about integrating this, and that, and writing symbols he did not understand. Nothing made sense to him anymore.
"Don't worry big brother, someday you'll understand and you'll be as good as me :)"

"Worst weekend ever", thought Jeremy.
"Phew, safe for now. Let's not tempt Melody further though", thought Philipp, slouching forward and awkwardly crossing his arms on his chest.