Cass Check

Cass leaned in, friendly as ever.

"Here's my whole job," she said. "Everybody's so relieved to get an answer that they forget to ask if the answer is believable. They do all this careful work, make one tiny slip somewhere, and end up with something silly — a person who's four hundred years old, a tank that takes five hours, a slice of pizza that costs a thousand dollars — and they write it down anyway, because they're just glad to be finished."

She grinned. "When I was little, I lost so many points to answers I knew were ridiculous if I'd only stopped to look. A test would ask how many buses you need for a field trip and I'd write 'two and a half buses.' Two and a half buses! If I'd just pictured it for one second, I'd have known. So I started picturing it. Every answer, before I trust it: does this match the real world? Could this actually happen?"

Bram frowned. "But the math said three hundred."

"The math said three hundred," Cass agreed. "But math is only as good as the steps you fed it. A sense-check catches the step that went wrong. Let's look."

So the circle went back, this time checking whether each piece made sense.

"The tap fills about one cup a minute," Tess read. "And the tank holds... wait." She stopped. "We wrote the tank as three hundred cups. But it's a small tank. Three hundred cups is huge — that's like a bathtub."

Omar checked the problem. "It says the tank holds sixty cups. We used three hundred by mistake — we grabbed the wrong number."

"So redo it with sixty," Cass said.

Sixty cups, one cup a minute. "Sixty minutes," Devi said. "One hour. To fill a small tank." She pictured it. "That makes sense. That's believable."

"And three hundred never was," Cass said gently. "Your sense-check caught a wrong number you'd copied. The math was fine. The ingredient was wrong — and only common sense could've spotted it."

Cass smiled as the circle stared at their corrected answer.

"See what just happened?" she said. "You were one second from writing down 'five hours to fill a small tank' and moving on. Not because you're bad at math — your steps were perfect. But you'd grabbed a wrong number at the start, and the only thing that could catch it wasn't more math. It was stopping to ask, 'wait, does this make sense?'"

Tess looked a little shaken. "We were so ready to just be done."

"Everybody always is," Cass said warmly. "That's exactly the moment mistakes sneak through — when you're tired and the answer's right there and you just want to stop. The sense-check costs you ten seconds. And it saves you from confidently writing down something that couldn't possibly be true." She tapped the corrected answer. "You didn't just get the right answer. You caught the wrong one yourselves, before anyone else saw it. That's a different kind of good."

Devi nodded slowly. "It felt kind of great, actually. Catching it."

"It's the best feeling," Cass said. "Way better than being told you're wrong later."