6 year old small cousin came flying across the room, landed heavily (she's not that small!) on me, gave me a moment to recover, and announced, 'Butterflies are symmetrical!'
Another cousin (now a lawyer) was watching one of the early moon shots on TV. Friend of her father said, 'Look Sabie, there's the rocket!' Sabie (2 and a half) looked at the screen and said, 'That's not the rocket, that's the lunar module.'
Same vein: Small thing in pushchair ignoring the world. Stout maiden aunt type pokes it, and tells it to 'Look at the gee-gee!' Small thing looks out of pushchair, says 'Horse' and goes back to ignoring everything.
On a personal note, I was asked (at 3 or 4) why I had almost all my toys spread about the floor. My reply: 'I'm making chaos!'