A 69, for starters

After March makes Serena cum, the latter smiles wide.

"I know what I need to teach you next."
"Oh yeah? What's that?"
"Well, it's why I love Math."

March is confused...until she ends up in a 69 with Serena on top of her licking her out.

March figures out the 'complex' rules of this game and starts to lick out Serena again.

She doesn't know why, but she needs to taste her more...and more.
You sneaky devil.

The pair roll over and March is on top now.

She even notices the camera...but says nothing...and doesn't stop.

After they both have a nice pair of orgasms, Serena says that she has one more thing to teach her.

March is happy to see what it is.

It isn't long before she's on her back with Serena rubbing her pussy against her own.

She likes tribbing.

March cums hard.
Serena cums hard.

"You're pretty good. Next time, I'll let you trib me."
"As long as he gets to watch us," March says, looking at the camera.

"Ha. You caught me," Serena says, "I'm going to lick out your little Sister while she watches this later."
"Sounds hot. I'll find Daphne, maybe. She's so hot."
"She is. But first, our Master has a mission for us."