Kate sighs, and rakes a hand through her hair. If the pile of exams she had just graded could talk they would either say that her entire class was made up of idiots or she was the worst teacher in existence.

But she knew it wasn't true! Just yesterday her class knew the material forwards, backwards and upside down. But when they got to the test? Nothing. Nada. Crickets. And years of kids coming through her classroom had proven she was an amazing teacher.

"Bad Day?"

Kate looks up as the man standing in her doorway speaks. "The worst," she answers.

He cocks that annoying, dimpled, childish grin that had always part annoyed and aroused her since the moment they met four years ago starting at the school at nearly the same time: she in fourth, he in second.

"Someone throw up in your face?" He asks, crossing the room to her desk, recalling a horrid memory from a past crop of second graders he had had in his class.

"No; that would have been an improvement over today," she deadpans, meeting his eyes. "Just frustrated. According to these tests, apparently I'm a horrible teacher." She drops her purple grading pen onto the desktop and falls into the back of her chair, not noticing the way his face softens, his eyes beaming out sympathy and reassurance to her.

"No, Kate, that's not true, not in the least." He reaches a hand over and places it on her shoulder, and she doesn't flinch away like she always had before. She lets him keep it there. "You're an amazing teacher! Everyone knows that; the kids freaking out over getting you as their new teacher is proof enough. We all have that time when it seems like we've failed because it looks like our kids aren't getting it–"

"And they know the material! But the test doesn't show that," Kate interrupts, slapping a hand on the pile of papers. "I just wish there was a better way to show that these kids know how to multiply fractions."

"Maybe there is," he says, pulling out his cell phone. After a minute a mischievous look comes to his eyes.

"I know that look," Kate says, sitting up a little straighter in her desk chair. "Nothing good ever comes out of that look. What's going on in that mind of yours, Castle?"

"Huh?" He asks, as if he had gotten lost in another world and suddenly realized she was still there. "Oh sorry, just checking something." He locks his phone before slipping it back into his pocket. "Do you remember there was a theory that said that if kids actively participated in their learning, they would understand it better?"

"Yes, I remember," she nods, her brow furrowing. "What does that have to do with my kids and their horrible test grades?"

"Beckett," Castle starts, half sitting on her desk, smirking down at her. "Do your kids like cookies?"

[] []

"Alright. Alright!" Castle hollers over the din of noise two classes could create. Once they quiet down, he starts again. "So today Ms. Beckett's class and us are gonna work on a project together. It involves fractions—," that elicits a groan from the older class, who were under the assumption that they were doing something fun with their Little Buddies, not math homework. "I know, I know: it's no fun. But trust me, this is gonna be fun." Castle smiles at his fellow teacher.

For the past week, they had been planning this little event as a way to make the math concept fun, to have the older kids teach the younger a harder concept, and also show that her class really did know what they were talking about.

"For our movie party tomorrow, we're gonna need snacks, right?" Kate continues where her partner left off. "So you guys are gonna make them! But to do that we have to double the recipes."

Kate goes on to explain how the kids will be divided into groups and either make cookies or brownies. They would have to use their knowledge of fraction to double the recipes, and then, after checking with an adult (who had the accurate calculations) that their work was right, they would get to make the treats.

The two teachers divide their classes into already predetermined groups, making sure an equal number of older and younger kids were in each group, and send them on their way.

The room fills once again with noise as the older kids from Kate's class teacher the younger how to double the recipe, and the younger attempt a skill they have yet to learn.

Her class is so good with his: taking things slow, and helping the younger kids if they make mistakes and cheering them on as they get answers correct and their confidence grows.

Soon the conversations turn to cheers as they groups get their work approved and are allowed to move to the team of parent volunteers to start preparing their treats.

More than once Kate hears her students say "This is fun!" or "Why can't math always be this cool" and it makes her smile.

"We did a good thing, Beckett," Castle tells her, smugly, as they step back for a minute to watch.

"We did," she nods. "Thanks."

"Always," comes his simple answer.

[] []

The next day, while their students eat their hand-made treats while watching "The Emperor's New Groove", Kate changes all the horrid test grades to one that better reflect her kids understanding of the concept, and Castle writes a lesson plan for the next week that includes fractions, now that he knows his kids can handle it.