"Do You See...." joke

One day a 6 year old girl was sitting in the classroom. The teacher was going to explain evolution to the children.
The teacher asked a little boy: Sonu do you see the tree outside?
Sonu: Yes.
Teacher: Tommy, do you see the grass outside?
Sonu: Yes.
Teacher: Go outside and look up and see if you can see the sky.
Sonu: OK. (He returned a few minutes later) Yes, I saw the sky.
Teacher: Did you see God?
Sonu: No.
Teacher: That's my point. We can't see God because he isn't there. He doesn't exist.
A little girl spoke up and wanted to ask the boy some questions.
The teacher agreed and the little girl asked the boy: Do you see the tree outside?
Sonu: Yes.
Little girl: Tommy do you see the grass outside?
Sonu: Yessssss (getting tired of the questions by this time)
Little girl: Did you see the sky?
Sonu: Yessssss
Little Girl: Tommy, do you see the teacher?
Sonu: Yes
Little Girl: Do you see her brain?
Sonu: No
Little Girl: Does that mean she doesn't have one?