"Do you know a heart has four rooms?"
"Yes. And blood goes from auricle to ventricle. But it doesn't go from right room to left room."
"Wow, I never knew that. Who told you?"
"Teacher! But you know something, teacher doesn't know anything."
"Because she showed us a heart, and it didn't even look like a heart."
"Maybe that is how a heart really looks."
"Then why does a heart has two round round on top and pokey-pokey at the bottom? Is that a different kind of heart?"
I shrugged. It is impossible to satisfy seven-year olds.