Black-white/white-black

My wife Lalitha used to teach my daughter when she was in the UKG class.

One day she was teaching opposites.

Black-white / White-black / Black-white/ White-black / Black-white

This was going on for sometime.

I asked her what she was upto. She said that she is teaching opposites.

Is it not enough if you said Black-white?

Yes, but if they ask the opposite of white?

Black-white / White-black / Black-white .......

I was amused.