-your 3 year old twins are arguing whether tomato is a fruit or a vegetable.
-your 3 year old twins are arguing whether the moon is following us, or leading us.
-your 11 month old twins have figured out they can move heavy objects "together" closer to the fireplace. Then one lies down on it, and signs or "tells" his brother to climb on his back to get to the things on the mantle.
-your 4 year old asks you what kind of matter is fire? Liquid or gaseous?
-your 4 year old tells a friend scared of the hurricane - "don't worry, a rainbow will come after the rain".