While walking back from the village up what Taf calls "the secret path":

Smudge: Look that fence!
Six: Oh yes!
Smudge: It's green.
Six: No, it's not green. It's wooden.
Smudge: Uh?
Six: It's made of wood.
Smudge: Oh.
Six: Do you know where wood comes from?
Smudge: Daddy got it!

:))