answer: Mason tells Phoebe that he has a big family.
documents: #Person1#: Hi, Mason!
  #Person1#: Oh, hi, Phoebe!
  #Person2#: Hey, in class today I heard you have a big family.
  #Person1#: That's right. I've got five brothers and six sisters.
  #Person2#: Wow! That's pretty big! Are you the eldest or the youngest?
  #Person1#: Neither. I'm the third eldest.