The joke's on the teacher

GRAMMAR IN ACTION

The passing lady mistakenly supposed that the woman
shouting from a window down the street was calling to
the little girl minding baby brother close by on the
curb. "Your mother is calling you," she said kindly.
The little girl corrected the lady:
"Her ain't a-callin' we. Us don't belong to she."

* * *

The teacher asked the little girl if she was going to
the Maypole dance. "No, I ain't going," was the reply.
The teacher corrected the child:
"You must not say, 'I ain't going,' you must say, 'I
am not going.' " And she added to impress the point:
"I am not going. He is not going. We are not going.
You are not going. They are not going. Now, dear,
can yon say all that?"
The little girl nodded and smiled brightly.
"Sure !" she replied. "They ain't nobody going."