All in a day's work

Child #1:  Do you have any books on entomology?

Me:  Do you mean insects?

Child #1:  No.

Me:  Do you mean words?

Child #2:  No.

Me:  Okay.  What's it about?

Child #1:  I think it's something about human...something.

Me:  How do you spell it?

Child #2 [slowly]:  A...

Child #1:  Is it about horoscopes?

Me.  Okay.  Astrology is about horoscopes.  Astronomy is about stars and constellations.  Anatomy is about the human body.  Entomology is about insects.  Etymology is about words.

Child #1:  It's astrology.

Me.  Okay, let's go look over here.