We have central air and were standing next to the running air conditioner.
Katie: What is that thing?
Me: The air conditioner
Katie: What does that do, condition the air?
Scot: No Katie, that keeps the house cool. Have you noticed that when it is hot outside, it is not hot in the house?
Katie: The air must be piped in somehow then.
Scot and I (in unison): Yes, through the vents.
Katie: Oh, now I get it. I only knew how window air conditioners worked.