The Opposite Game

I was trying to make my 3 years 7 months old daughter learn opposite words the fun way.

Mummy : Kate, let's play the opposite game.
Kate : Okay!
Mummy : What's the opposite of "big"?
Kate : Small.
Mummy : Very good! How about "long"?
Kate : Short.
Mummy : Tall?
Kate : Short.
Mummy : Special?
Kate : Ordinary.
Mummy : Straight?
Kate : Not straight at all.
Mummy : Huh??... ahhahaha!!!